MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Scripta Materialia' source. Wed, 02 Mar 2011 15:11:43 +0100 http://www.scriptamat.org/article/PIIS1359646210007013/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097699 Sun, 24 Oct 2010 14:07:16 +0100 4097699 http://www.scriptamat.org/article/PIIS1359646210006317/abstract?rss=yes Using temperature-dependent X-ray diffraction and magnetization measurements, a reversible face-centered cubic (fcc) to body-centered cubic (bcc) structural transformation was confirmed in freestanding epitaxially grown films after lift-off from their MgO (100) substrates—a transformation generally considered irreversible in bulk samples. The latter is accompanied by a distinct change of the sample magnetization. In contrast, substrate constraints were found to suppress the thermoelastic fcc to bcc transformation in substrate-attached films. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097722 Sun, 19 Sep 2010 23:00:00 +0100 4097722 http://www.scriptamat.org/article/PIIS1359646210006184/abstract?rss=yes Nanocrystalline metals generally exhibit high strengths and good fatigue resistance. Their strengthening scales with the inverse of grain size through square root dependence down to grain sizes of ∼20nm, representing the well-known Hall–Petch relation. Here we show that in surface-dominated structures with sub-micron dimensions, i.e. nanopillars, 60nm grained Ni–W alloys exhibit lower tensile strengths with decreasing pillar diameter, form shear bands and undergo mechanical twinning. Moreover, there appears to be a transition in the deformation mechanism – from dislocation-driven deformation in pillars with diameters larger than 100nm to grain-boundary-mediated deformation in pillars of 100nm and below, including grain rotation and grain-boundary migration, processes previously obs... Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097719 Sun, 19 Sep 2010 23:00:00 +0100 4097719 http://www.scriptamat.org/article/PIIS1359646210006238/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980709 Sat, 18 Sep 2010 10:40:21 +0100 3980709 http://www.scriptamat.org/article/PIIS135964621000641X/abstract?rss=yes The combination of non-conventional methods of synthesis (mechanosynthesis) and sintering (SPS) has been used for the preparation of nanostructured BiScO3–PbTiO3 ceramics with tailored grain size. The key to control grain growth in the nanoscale is to achieve a significant densification during initial stages of the SPS, mainly by particle rearrangement under pressure, before thermally activated processes are triggered. The temperature dependence of dielectric permittivity suggests that the ferroelectric transition might have vanished for the material with the smallest grain size. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097724 Thu, 16 Sep 2010 23:00:00 +0100 4097724 http://www.scriptamat.org/article/PIIS1359646210006305/abstract?rss=yes We report direct observation of the formation of threading dislocations from stacking faults in GaN layers grown on (0001) sapphire by hydride vapor phase epitaxy. High-resolution electron microscopy revealed that the stacking sequence of the stacking fault is “AaBbCcBbAa” and threading dislocations are generated from Shockley partials bounding the stacking fault. A model is proposed to explain how such stacking faults lead to the generation of threading dislocations. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097723 Thu, 16 Sep 2010 23:00:00 +0100 4097723 http://www.scriptamat.org/article/PIIS1359646210006329/abstract?rss=yes A novel Zr-based bulk metallic glass composite was fabricated using stainless steel capillaries as the reinforcement. Large plasticity (14%) was achieved in the composite with a reinforcement volume fraction of 38%. The high plasticity observed can be attributed to the formation of small glass fibers encapsulated by the steel capillaries, which promotes multiple shear bands in both metallic glass matrix and the fibers themselves. A new parameter was also proposed to approximately evaluate the reinforcement efficiency. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097721 Thu, 16 Sep 2010 23:00:00 +0100 4097721 http://www.scriptamat.org/article/PIIS1359646210006330/abstract?rss=yes Structural evolution of an Au-based bulk metallic glass (BMG) after severe plastic deformation (SPD) was investigated. The newly formed glass contains high-density shear bands, a reduced ordering and a concomitant excess free volume. Moreover, it exhibits a less-changed local structure even in the supercooled liquid region, but a reduced thermal stability reflected in an accelerated crystal nucleation and growth process. These results suggest that SPD modifies the atomic structure of BMGs by localized shear band formation, thus producing so-called nanoglasses. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097720 Thu, 16 Sep 2010 23:00:00 +0100 4097720 http://www.scriptamat.org/article/PIIS1359646210006172/abstract?rss=yes An improved model for bainite formation via a displacive mechanism is presented. The model incorporates a temperature-dependent expression for the potential nucleation site density and a linear scaling function to predict the maximum volume fraction of bainite. The model has been validated with respect to the experimental data of three high-silicon steels from the literature and has been found to perform reasonably well for several isothermal transformation cases. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097718 Wed, 15 Sep 2010 23:00:00 +0100 4097718 http://www.scriptamat.org/article/PIIS1359646210006123/abstract?rss=yes Bhadeshia recently claimed that the two-step theory of martensitic transformation was mathematically incorrect and incapable of making predictions about the observed pole figures. The present paper argues that his comments are not justified and that his alternative propositions do not agree with the observations. The continuous rotations observed in the pole figures do not result from the tempering treatments but from the plastic accommodation of the lattice transformation during the γ→ε→α sequence. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097726 Tue, 14 Sep 2010 23:00:00 +0100 4097726 http://www.scriptamat.org/article/PIIS1359646210006147/abstract?rss=yes Commercially pure (CP) Ti was subjected to a complex severe plastic deformation (SPD) processing route consisting of equal channel angular pressing, swaging and drawing, resulting in the formation of a homogeneous ultra-fine-grained (UFG) microstructure showing a very high strength. The significant anisotropy of mechanical properties found in the processed rod is related to a very strong crystallographic texture developed during SPD processing. The features of plastic deformation of the UFG CP Ti are discussed with respect to its crystallographic texture. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097717 Mon, 13 Sep 2010 23:00:00 +0100 4097717 http://www.scriptamat.org/article/PIIS1359646210006160/abstract?rss=yes Damage evolution during very high cycle fatigue (VHCF) in AXJ530 die-cast magnesium alloy was studied in situ using nonlinear ultrasonic measurements via analysis of the feedback signal of a closed-loop ultrasonic fatigue system. Variations in acoustic nonlinearity with fatigue cycles revealed cyclic hardening/softening during early fatigue life ( (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097716 Mon, 13 Sep 2010 23:00:00 +0100 4097716 http://www.scriptamat.org/article/PIIS1359646210006135/abstract?rss=yes The compressive behavior of closed-cell copper-coated carbon fiber/aluminum composite foam with 1 and 5wt.% fibers was assessed under quasi-static and high-strain-rate loading conditions. The 5wt.% fiber/aluminum foam exhibits higher plastic collapse stress. The failure modes of fibers in the matrix were discussed. A strain-rate effect was demonstrated for fiber/aluminum foam. The strain-rate effect was more apparent at strain rates in the ∼ks−1 range and is attributed to the rate sensitivity of dense fiber/aluminum composite and to the foam structure. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097715 Thu, 09 Sep 2010 23:00:00 +0100 4097715 http://www.scriptamat.org/article/PIIS1359646210006111/abstract?rss=yes Two-phase ultrafine-grained (UFG) aluminum alloys with different precipitate and low-angle boundary distributions were examined for their monotonic stress–strain behavior. Precipitates in combination with low-angle grain boundaries were found to determine the deformation micromechanism. It is proposed that thermally activated vacancy movement plays a central role in this regard. The experimental stress–strain curves matched well with the trend predicted by a modified Blum–Zheng model based on vacancy-assisted dislocation annihilation mechanism. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097714 Thu, 09 Sep 2010 23:00:00 +0100 4097714 http://www.scriptamat.org/article/PIIS1359646210006093/abstract?rss=yes The interdiffusion behavior of the Ni3Al–Mo ternary system at 1423, 1473 and 1523K was studied using Ni3Al/Ni3Al–Mo single-phase diffusion couples. The concentration-dependent interdiffusion coefficients were calculated over the whole diffusion range, and the average ternary interdiffusion coefficients were carefully determined in the middle of the diffusion zone. These ternary coefficients were also examined to estimate tracer diffusion coefficients of Mo in the Ni3Al phase. The results were also used to explain the diffusion behavior of Mo in the Ni3Al-based superalloy IC-6. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097713 Wed, 08 Sep 2010 23:00:00 +0100 4097713 http://www.scriptamat.org/article/PIIS135964621000610X/abstract?rss=yes The effect of the roll speed ratio (SR) on the microstructure, texture and mechanical properties of commercially pure Ti during differential speed rolling was examined at 673K in a wide range of SRs between 1 and 5 to produce Ti sheets with an ultrafine-grained microstructure exhibiting high strength. At an SR of 5, a defect-free sheet with shear bands and ultrafine grains homogeneously distributed over the entire thickness of the sheet could be fabricated through a single rolling pass. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097712 Wed, 08 Sep 2010 23:00:00 +0100 4097712 http://www.scriptamat.org/article/PIIS1359646210006081/abstract?rss=yes Young’s moduli of amorphous Cu–Zr thin films have been determined with unprecedented compositional resolution, via combinatorial film deposition and force–deflection measurements of microscale cantilevers. This elastic property increased monotonically with increasing Cu content. Such cantilever-based surveys of compositional libraries are considerably more rapid than that required of bulk samples. Additionally, interpretation of the film elastic modulus Ef via this approach is advantageous over indentation-based methods, particularly in terms of straightforward calculation that does not require knowledge of the glass’s Poisson’s ratio. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097710 Mon, 06 Sep 2010 23:00:00 +0100 4097710 http://www.scriptamat.org/article/PIIS135964621000607X/abstract?rss=yes Stationary shoulder friction stir welding (SSFSW) has been used to join 6mm thick AA6082. The current investigation shows that the deformation through the plate thickness is dominated by the probe of the tool with very little effect of the static shoulder at the top surface. This implies that the use of the SSFSW tool can result in a nugget completely dominated by the probe through the thickness. The SSFSW tool is proposed for processing of aluminium for enhanced formability. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097711 Sun, 05 Sep 2010 23:00:00 +0100 4097711 http://www.scriptamat.org/article/PIIS1359646210006056/abstract?rss=yes The changes in anisotropic hardness and indentation modulus induced by plasma nitriding at 400°C of a 316L polycrystalline austenitic stainless steel are analyzed. The dependence of hardness and elastic modulus modifications on the crystallographic orientation is investigated through instrumented indentation and electron backscattering diffraction. Both hardness and indentation modulus exhibit an inverted anisotropy compared to the untreated 316L, likely associated with the presence of the N atoms in interstitial sites. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097709 Sun, 05 Sep 2010 23:00:00 +0100 4097709 http://www.scriptamat.org/article/PIIS1359646210006068/abstract?rss=yes The microstructure and mechanical properties of extruded Mg94Ni3Y1.5CeMM1.5 alloy were evaluated between 250 and 400°C. The alloy exhibited superplasticity between 300 and 400°C. Superplastic deformation was characterized by the refinement of coarse second-phase particles and their continuous redistribution in the magnesium matrix. The equiaxed structure of the magnesium matrix in the deformed samples as well as the stress exponent close to 2 indicated that grain boundary sliding was the mechanism controlling the superplastic deformation. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097708 Sun, 05 Sep 2010 23:00:00 +0100 4097708 http://www.scriptamat.org/article/PIIS135964621000597X/abstract?rss=yes In this paper, we study the glide force due to stress on the constituent dislocations of slightly perturbed symmetric low-angle tilt boundaries. We show that the stabilizing force comes from both the long-range interaction of the constituent dislocations and their local line tension effect. We also present a continuum model for this glide force. The obtained results and continuum model provide a basis for further understanding of the stress-driven migration of distorted grain boundaries. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097701 Sun, 05 Sep 2010 23:00:00 +0100 4097701 http://www.scriptamat.org/article/PIIS1359646210005907/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3932999 Sat, 04 Sep 2010 09:17:16 +0100 3932999 http://www.scriptamat.org/article/PIIS1359646210006020/abstract?rss=yes The difference in the d-spacing change during diffusional and displacive transformation, obtained during continuous cooling processes, was characterized using a hybrid in situ observation system that we have developed. The d-spacing change in an austenite phase in the diffusional transformation was found to be discontinuous compared to that in the displacive transformation. This difference reflected the carbon partitioning behaviour, and the hybrid system enabled the tracking of transformation behaviours in both real and reciprocal lattice space. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097707 Wed, 01 Sep 2010 23:00:00 +0100 4097707 http://www.scriptamat.org/article/PIIS1359646210006044/abstract?rss=yes Microtensile experiments and electron microscopy have been utilized to characterize the mechanical behavior of nanocrystalline Pt films. The behavior can be described as high strength with limited strain to failure. The tensile deformation triggers a microstructural evolution increasing the grain size from 20nm in the initial state to 33nm in the deformed state. This observation of grain growth at a homologous temperature of 0.146 provides further evidence of the role of mechanical stress in initiating grain growth in nanocrystalline metals. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097706 Wed, 01 Sep 2010 23:00:00 +0100 4097706 http://www.scriptamat.org/article/PIIS1359646210006019/abstract?rss=yes Positron annihilation spectroscopy was performed to study the microstructure of peak aged Al–Zn–Mg–Cu alloy. Applying artificial ageing at different temperatures, the solute content around vacancies is found to be increased compared to as-quenched state. The similarity of vacancy surroundings of all artificially aged states, except for over-aged ones, suggests that peak strength is caused not only by η′ precipitates but also by GPII zones. Moreover, η′ precipitates produced by artificial aging at 403K are apparently coherent with the Al matrix. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097705 Wed, 01 Sep 2010 23:00:00 +0100 4097705 http://www.scriptamat.org/article/PIIS1359646210006032/abstract?rss=yes Monolithic ZrB2 ceramic and ZrB2–20vol.% SiC composite were joined to themselves using pure nickel powder. The interfacial phenomena were observed and analyzed. The joining effects were evaluated by shear strength. Resulting from the special interfacial microstructure, the shear strength of ZrB2/Ni/ZrB2 system was as high as 59.7±5.3MPa. In the ZrB2–SiC/Ni/ZrB2–SiC system, the reaction between Ni and SiC resulted in a homogeneous joint composition, which was beneficial to the joining effects. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097704 Wed, 01 Sep 2010 23:00:00 +0100 4097704 http://www.scriptamat.org/article/PIIS1359646210005968/abstract?rss=yes A cold-rolled metal sheet is usually of high strength but low plasticity due to the onset of premature local necking. Here, we reveal that the tensile plasticity of cold-rolled Cu can be effectively enhanced by a layered structure stacked alternately by thicker Cu and thinner Al layers. The layer interface in the composite strongly constrains and delays the development of premature local necking of the cold-rolled Cu layer. A potential way to improve plasticity without losing strength is suggested. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097703 Tue, 31 Aug 2010 23:00:00 +0100 4097703 http://www.scriptamat.org/article/PIIS1359646210005993/abstract?rss=yes Currently friction stir welding tools are designed by trial and error. Here we propose and test a criterion for the design of a tool shoulder diameter based on the principle of maximum utilization of supplied torque for traction. The optimum tool shoulder diameter computed from this principle using a numerical heat transfer and material flow model resulted in best weld metal strength in independent tests and peak temperatures that are well within the commonly encountered range. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097702 Tue, 31 Aug 2010 23:00:00 +0100 4097702 http://www.scriptamat.org/article/PIIS1359646210006007/abstract?rss=yes The domain orientation distributions around the loaded crack tip in a poled piezoelectric ceramic were measured in situ by using a high-energy synchrotron X-ray source. The results show the dynamic domain switching behavior around the switching zone. The relationship between the stress intensity factor and switching zone is revealed. During mechanical loading, the domain switching zone significantly enlarges with an increase in the stress intensity factor. Moreover, the mechanical depoling effect generated by the stress around the crack tip is detected. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097700 Tue, 31 Aug 2010 23:00:00 +0100 4097700 http://www.scriptamat.org/article/PIIS1359646210005981/abstract?rss=yes This study seeks to understand the influence of the growth rate R on microstructure evolution and grain refinement in Ti–6Al–4V–0.1B alloy using directional solidification experiments and microstructural characterization. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044990 Tue, 31 Aug 2010 23:00:00 +0100 4044990 http://www.scriptamat.org/article/PIIS1359646210005841/abstract?rss=yes The kinetics of accumulation of martensite/austenite during the direct/reverse two-stage B2–R–B19′ martensitic transformation in NiTi has been studied by means of resistance measurements during interruptions of cooling/heating scans. Experimental results indicate that the R–B19′ transformation is isothermal, whereas both direct and reverse B2–R and R–B2 transformations are perfectly athermal. The isothermal accumulation of the R-phase is also detected during B19′–R transformation. A good correspondence exists between the rate of the isothermal transformation and the transformation rate in an uninterrupted cooling cycle. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044989 Tue, 31 Aug 2010 23:00:00 +0100 4044989 http://www.scriptamat.org/article/PIIS135964621000583X/abstract?rss=yes Mechanical and shape memory properties of Ni43Co7Mn39Sn11 metamagnetic shape memory sintering compacts, fabricated by pressureless sintering, were investigated. With sintering time the porosity drastically decreases and the ductility is significantly enhanced compared to the samples obtained by conventional induction melting. Moreover, the fracture strain in the specimen sintered at 1173K for 144h is almost the same as that in the high density sintering compacts by spark plasma sintering. Interestingly, the shape memory effect decreases with decreasing porosity. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044988 Tue, 31 Aug 2010 23:00:00 +0100 4044988 http://www.scriptamat.org/article/PIIS1359646210005828/abstract?rss=yes In situ transmission electron microscopy investigations were carried out on a supersaturated nitrogen–ferrite to characterise the precipitation kinetics of α″-Fe16N2 nitrides at 85°C. The coarsening behaviour consists of two stages. The first stage obeys the LSW theory and the coarsening rate was determined as 11.2nm3s−1. The second stage corresponds to the stabilization of coarsening, and was assumed to be related to the coherency loss between the precipitates and the matrix. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044987 Tue, 31 Aug 2010 23:00:00 +0100 4044987 http://www.scriptamat.org/article/PIIS1359646210005804/abstract?rss=yes The evolution of morphology during directional solidification is investigated in terms of the interaction between bubbles and the solid–liquid interface. The results reveal that the solid phase grows along the bubble boundary to form solid envelopes and a liquid gap. As the interface velocity increases, the expansion coefficients of bubbles increase continually, and then decrease. The solidification microstructures of bubbles transform in the sequence water-drop→elongated→irregular with increasing interface velocity. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044986 Sun, 29 Aug 2010 23:00:00 +0100 4044986 http://www.scriptamat.org/article/PIIS1359646210005816/abstract?rss=yes Ag nanoink sintering kinetics and subsequent melting is studied using in situ synchrotron-based X-ray diffraction. Direct observations of Ag nanoink sintering on Cu demonstrate its potential for materials joining since the Ag nanoink sinters at low temperatures but melts at high-temperatures. Results show low expansion coefficient of sintered Ag, nonlinear expansion as Ag densifies and interdiffuses with Cu above 500°C, remelting consistent with bulk Ag, and eutectic reaction with Cu. The results demonstrate the usefulness of Ag nanoink as a high-temperature bonding medium. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044985 Sun, 29 Aug 2010 23:00:00 +0100 4044985 http://www.scriptamat.org/article/PIIS1359646210005798/abstract?rss=yes Internal damage below the fracture surface of a multiaxial specimen made of twinning-induced plasticity (TWIP) steel was observed by three-dimensional X-ray microtomography as very elongated “primary” voids. Specific tools for the local damage analysis were developed. A gradient in void volume fraction was measured from the fracture surface down to the bulk of the scanned volume (from ∼0.06% to 90% in area fraction), indicating strongly localized final fracture. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044984 Thu, 26 Aug 2010 23:00:00 +0100 4044984 http://www.scriptamat.org/article/PIIS1359646210005737/abstract?rss=yes The influence of W, Ta, Ti, Nb, V, Si, Mo, Ir and Cr on the high temperature properties of γ/γ′-strengthened Co–Al–W superalloys was investigated. All alloys exhibited a γ/γ′ microstructure with remarkably differing γ′ volume fractions. W, Ta, Ti, Nb and V increased the γ′ volume fraction and γ′ solvus temperature. An increased W content and alloying of additional elements, except Ir, decreased the liquidus temperature. First creep experiments revealed a creep strength comparable with polycrystalline Ni-base superalloys and the importance of grain boundary strengthening. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044978 Thu, 26 Aug 2010 23:00:00 +0100 4044978 http://www.scriptamat.org/article/PIIS1359646210005762/abstract?rss=yes We investigate the phase separation of the solid solution CoTi(1−x)MnxSb into the two Heusler compounds CoTiSb and CoMnSb. Energy-dispersive X-ray spectroscopy measurements on the two-phase material reveal the presence of size- and shape-tunable CoTiSb regions in a CoMnSb matrix. We demonstrate that the formed phase and grain boundaries have a considerable influence on the phonon scattering processes, which leads to a reduction in the thermal conductivity by a factor of three compared to single-phase CoTiSb. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044983 Wed, 25 Aug 2010 23:00:00 +0100 4044983 http://www.scriptamat.org/article/PIIS1359646210005750/abstract?rss=yes A quantum-continuum multiscale coupling of Kohn–Sham density functional theory to continuum material is presented that can handle mechanics problems in metals when long-range stress fields are present, such as occurs for dislocations and cracks. The method has quantifiable and controllable coupling errors that can be minimized at computationally tractable system sizes. Using both generalized gradient and local density approximation exchange–correlation functionals, the nucleation of a dislocation from a crack tip in aluminum is then predicted. Both functionals yield similar results, and predictions using Rice’s continuum Peierls model are within 20% of the quantum values. This multiscale method is easily extendable to crack-tip problems involving alloys and chemical embrittlements. (... Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044982 Wed, 25 Aug 2010 23:00:00 +0100 4044982 http://www.scriptamat.org/article/PIIS1359646210005774/abstract?rss=yes The addition of Mg significantly improves the strength of the 50vol.% TiCx/Al composite, and the ultimate compression strength of the TiCx/Al–Mg composite is about 353MPa higher than that of the TiCx/Al composite. The addition of Zn improves the ductility of the composite, the fracture strain of which increases from 7.53% to 9.35%. With the addition of Sn, the TiCx/Al–Sn composite exhibits the highest work-hardening capacity, which is about 3.64 times higher than that of the TiCx/Al composite. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044981 Wed, 25 Aug 2010 23:00:00 +0100 4044981 http://www.scriptamat.org/article/PIIS1359646210005713/abstract?rss=yes The role of imposed strain on the room temperature time-dependent deformation behavior of bulk metallic glasses (BMGs) was systematically investigated through spherical nanoindentation creep experiments. The results show that creep occurred even at very low strains within elastic regimes and, interestingly, a precipitous increase in creep rate was found in plastic regimes, with BMG that had a higher free volume exhibiting greater creep rates. The results are discussed in terms of prevailing mechanisms of elastic/plastic deformation of amorphous alloys. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044980 Wed, 25 Aug 2010 23:00:00 +0100 4044980 http://www.scriptamat.org/article/PIIS1359646210005725/abstract?rss=yes A definitive understanding of how grain size affects the corrosion rate and passivity of different metallic alloys has not been developed to date. A review of the pertinent literature, combined with the authors’ works, reveals that a relationship exists between corrosion rate and grain size. This phenomenon correlates with total grain boundary length and reveals an important fundamental relationship that can be exploited for material durability and design. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044979 Wed, 25 Aug 2010 23:00:00 +0100 4044979 http://www.scriptamat.org/article/PIIS1359646210005749/abstract?rss=yes We present a combination of experiments and theoretical simulations to investigate the optical response of Au/Ag alloyed hollow nanoshells. The results show that two distinct plasmon resonances corresponding to the dipolar and quadrupolar modes appear in the extinction spectra of nanoshells. As the thickness of the shell decreases the multiple modes consistently red shift and the resonant intensity increases. The results are validated by the calculated electric field distribution of nanoshells. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044977 Wed, 25 Aug 2010 23:00:00 +0100 4044977 http://www.scriptamat.org/article/PIIS1359646210005531/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895746 Tue, 24 Aug 2010 09:54:03 +0100 3895746 http://www.scriptamat.org/article/PIIS1359646210005671/abstract?rss=yes The influence of high current on the structure and integration of carbon nanotubes during spark plasma sintering is discussed in this paper. Observation of the microstructure showed that most carbon nanotubes burn out or diffuse into alumina grains when composite powders directly contact the graphite plungers of the sintering die. This structural damage was largely avoided when two layers of insulating BN were used to block the high-density current. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044974 Sun, 22 Aug 2010 23:00:00 +0100 4044974 http://www.scriptamat.org/article/PIIS1359646210005683/abstract?rss=yes SiC/20vol.% C(graphite) composites were fabricated by plasma-activated sintering. The Vickers hardness was 5.8GPa because of the existing of graphite and weak interface between the graphite and the SiC. Specimens were treated by silicon infiltration, which improved the surface Vickers hardness (24GPa). X-ray diffraction results showed that the graphite in the surface reacted with liquid silicon to form SiC. Scanning electron microscopic observation indicated that the continuous film was dense and approximately 25μm in thickness in the top surface. For the hardening surface, the oxidation and wear resistance were improved. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044973 Thu, 19 Aug 2010 23:00:00 +0100 4044973 http://www.scriptamat.org/article/PIIS1359646210005610/abstract?rss=yes This study examined the ternary Ni2SnP layer in Sn–3.5Ag–0.7Cu/electroless Ni (P) solder joints using in situ transmission electron microscopy (TEM). TEM confirmed the formation of an Ni2P phase underneath the ternary Ni2SnP after reflowing. We can directly observe the Sn diffused into Ni2P to form Ni2SnP during annealing in TEM. These results suggested that the ternary Ni2SnP forms through the diffusion of Sn into Ni2P. In addition, small Kirkendall voids were newly formed in the ternary Ni2SnP layer after annealing in TEM. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980728 Thu, 19 Aug 2010 23:00:00 +0100 3980728 http://www.scriptamat.org/article/PIIS135964621000566X/abstract?rss=yes The effects of hydrogen on the deformation mechanism of 〈001〉-oriented single crystals of Hadfield steel were studied under tension at temperatures of 77 and 300K. An increase in intensity of twinning was observed for samples charged with hydrogen, and it is assumed that this is the reason for the increase in elongation to fracture. Despite the high elongation to failure, the fracture surfaces displayed a brittle component. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044976 Wed, 18 Aug 2010 23:00:00 +0100 4044976 http://www.scriptamat.org/article/PIIS1359646210005695/abstract?rss=yes The development of shear bands in partially solid alloys is investigated during the deformation of a magnesium alloy at ∼45% solid during equiaxed solidification. Results show that shear bands initiate after reaching the peak stress and then increase in thickness during strain softening from ∼10 to ∼16 mean grains thick. Once shear bands become fully developed, shear continues at approximately constant stress and volume. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044975 Wed, 18 Aug 2010 23:00:00 +0100 4044975 http://www.scriptamat.org/article/PIIS1359646210005701/abstract?rss=yes The creep property in the Mg–6Al–3Ca alloy is improved by the addition of Mn. Spherical precipitates form after casting in 0.5Mn alloy. The number density and radius hardly change from the as-cast state. They are segregated to the interface of the planar Al2Ca phase, leading to strain fields around the particle. The precipitation of the Al2Ca phases and the spherical precipitates can significantly enhance the creep property. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044972 Wed, 18 Aug 2010 23:00:00 +0100 4044972 http://www.scriptamat.org/article/PIIS1359646210005634/abstract?rss=yes This study suggests that the mechanical properties of nanoporous metals depend not only on the relative density, ligament size and morphology, but also on the structure inside ligaments. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044971 Tue, 17 Aug 2010 23:00:00 +0100 4044971 http://www.scriptamat.org/article/PIIS1359646210005658/abstract?rss=yes We examine the processes of spherical indentation and tension in Ni nanowires and thin films containing random distributions of nanoscale grains by molecular dynamics simulations. It is shown that the resistance to nanoindentation of nanocrystalline Ni nanowires with diameters of 12 and 30nm tends not to depend on the wire diameter and free surfaces, contrary to nanoindentation in single-crystalline nanowires. Accommodation of plastic deformation by grain boundary sliding suggests a mitigation strategy for sample boundary effects in nanoscale plasticity. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980735 Tue, 17 Aug 2010 23:00:00 +0100 3980735 http://www.scriptamat.org/article/PIIS1359646210005622/abstract?rss=yes The binder phase grains in WC–Co-based cemented carbides are generally larger than 10μm. We have developed a method for measuring this grain size using electron backscatter diffraction. The results indicate that a material that has a high carbon content, is slowly cooled, has a small WC grain size or has a small amount of binder phase will have a small binder phase grain size, which means that the binder phase was more easily nucleated. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044970 Sun, 15 Aug 2010 23:00:00 +0100 4044970 http://www.scriptamat.org/article/PIIS1359646210005440/abstract?rss=yes Magnetization and resistivity were measured as a function of temperature in polycrystalline Ni–Mn–Sn Heusler alloys with a magnetocrystalline first order phase transition. At external magnetic fields (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044969 Sun, 15 Aug 2010 23:00:00 +0100 4044969 http://www.scriptamat.org/article/PIIS1359646210005415/abstract?rss=yes Microstructure and texture evolution during non-isothermal annealing of a precipitation-hardenable aluminum alloy with varying levels of cold reduction has been studied. It is found that a certain level of cold reduction is required to achieve a fully recrystallized, fine grained microstructure with a weak texture. Restoration mechanisms in non-isothermal annealing consist of extended recovery followed by grain growth in some preferentially oriented deformed grains at low annealing temperatures and discontinuous recrystallization with formation of randomly oriented grains at higher annealing temperatures. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044968 Sun, 15 Aug 2010 23:00:00 +0100 4044968 http://www.scriptamat.org/article/PIIS1359646210005609/abstract?rss=yes A unique technique was developed to render dense mullite ceramics with an in situ tough interlocking structure. The microstructures were achieved by using a commercial mullite powder mechanoactivated with tungsten carbide milling media as seeds and a gel-derived nanosized mullite precursor as a matrix. Only less than 1wt.% seed was sufficient to trigger the in situ formation of mullite whiskers uniformly distributed in a dense submicron-grained mullite matrix after sintering at 1450°C for 5h. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980734 Sun, 15 Aug 2010 23:00:00 +0100 3980734 http://www.scriptamat.org/article/PIIS1359646210005476/abstract?rss=yes The ball milling conditions in the preparation of rare earth aluminum hydrides from NaAlH4 and rare earth chlorides have a significant influence on product formation. Defined milling times and appropriate rotational speeds are required to obtain the desired products. It has been shown that starting directly from Na3AlH6 does not lead to the formation of REAlH6. Starting from rare earth iodides instead of chlorides allows dissolution of the alkali metal iodide formed and, therewith, the preparation of salt-free rare earth aluminum hydrides. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980733 Sun, 15 Aug 2010 23:00:00 +0100 3980733 http://www.scriptamat.org/article/PIIS1359646210005488/abstract?rss=yes We report the coercivity enhancement of hydrogenation–disproportionation–desorption–recombination processed Nd–Fe–B nanocrystalline powders from 1321 to 1552kAm−1 (19.5kOe) by the grain boundary diffusion of Nd–Cu melts with hyper-eutectic compositions. A distinct Nd-rich grain boundary phase was observed after the diffusion process by scanning electron microscopy and transmission electron microscopy; however, atom probe tomography indicated that the change in composition of the grain boundary phase was not significant. The mechanism of the coercivity enhancement is discussed based on these results. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980732 Sun, 15 Aug 2010 23:00:00 +0100 3980732 http://www.scriptamat.org/article/PIIS1359646210005452/abstract?rss=yes We report molecular dynamics simulation studies demonstrating the feasibility of a design methodology for forming metallic nanotubes and nanocoils via spontaneous self-rolling-up of free-standing, initially planar (001)/(111) bilayer nanofilms. Our studies on aluminum reveal that bilayer self-rolling is controlled by both energetic and kinetic processes accompanying the spontaneous structural reorientation of the (001) oriented top layer to the (111) orientation of the substrate layer. The radii of the resulting structures are determined by bilayer thickness and temperature. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980731 Sun, 15 Aug 2010 23:00:00 +0100 3980731 http://www.scriptamat.org/article/PIIS1359646210005464/abstract?rss=yes Dynamic electrical contacts may lose their conductivity due to wear or oscillation-induced defects (primarily dislocations). Nano-twinned Cu appears to be a promising candidate for dynamic contacts. Molecular dynamics simulations have been conducted to study defect generation in nano-twinned Cu during wear, in comparison with nano-grained Cu and single crystal Cu. Defect generation in the former was lower during bidirectional sliding wear. The Bauschinger effect was noticed during bidirectional sliding, demonstrated by a decrease in the density of residual defects. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980730 Sun, 15 Aug 2010 23:00:00 +0100 3980730 http://www.scriptamat.org/article/PIIS1359646210005439/abstract?rss=yes The influence of strain rate and temperature during friction stir processing (FSP) on the texture and tensile behavior of a Mg alloy has been investigated. By varying key processing parameters systematically, i.e. rotation and travel rates of the tool, a series of FSP specimens were prepared with a wide range of thermo-mechanical inputs in terms of the Zener–Hollomon parameter (Z). Neutron diffraction results showed a dramatic change in texture as Z increased. The resulting tensile behavior in the stir zone also illustrates the influence of Z. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980729 Sun, 15 Aug 2010 23:00:00 +0100 3980729 http://www.scriptamat.org/article/PIIS1359646210005403/abstract?rss=yes The effect of nickel contamination on the electrical characteristics of a (110)/(100) interfacial grain boundary in p-type direct silicon bonded wafers has been investigated by current/capacitance–voltage deconvolution. It was found that, compared with a clean grain boundary, nickel could increase the density of grain boundary states, and the corresponding hole capture cross-section was increased by one order of magnitude. Shockley–Read–Hall simulation verified that these nickel-related grain boundary states could cause a larger leakage current under reverse bias than that for a clean grain boundary. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980726 Sun, 15 Aug 2010 23:00:00 +0100 3980726 http://www.scriptamat.org/article/PIIS1359646210005427/abstract?rss=yes Embrittlement at 475°C was mapped in ferritic ternary alloys with a wide composition range of Fe–(10–30)Cr–(0–20)Al (at.%) using a diffusion multiple technique. A large solid solution of Al suppresses the 475°C embrittlement, while a small solid solution of Al promotes embrittlement. Transmission electron microscopy observations on aged samples suggest that suppression of the embrittlement due to Al addition can be attributed to the suppression of phase separation of the ferrite phase into the two phases Fe-rich ferrite and Cr-rich ferrite. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980727 Thu, 12 Aug 2010 23:00:00 +0100 3980727 http://www.scriptamat.org/article/PIIS1359646210005385/abstract?rss=yes A size effect study was conducted on [001] oriented vanadium nanopillars that were synthesized from both a thin film and a bulk crystal. The results indicate that a size-dependent deformation behavior exists for vanadium; the smaller nanopillars displayed discrete strain bursts and higher stresses during deformation. The size effect exponent is found to be 0.79, and the results are compared with previous reports on other body-centered cubic (bcc) metals: Nb, Ta, Mo and W. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044967 Wed, 11 Aug 2010 23:00:00 +0100 4044967 http://www.scriptamat.org/article/PIIS1359646210005312/abstract?rss=yes We report a seven-layered modulated monoclinic crystal structure in the Ni-rich, Ga-poor Ni53.5Mn26.0Ga20.5 alloy. The present composition exhibits coupled magneto-structural transformation around 350K. Multi-mode twinning with a predominance of crossing twins, indicative of low residual stresses, is observed. A significant shape memory effect of 1.6% and a high strain recovery ratio of 89% are achieved in the polycrystalline specimen at low stresses, owing to lower twinning energies arising from lattice modulation. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980719 Wed, 11 Aug 2010 23:00:00 +0100 3980719 http://www.scriptamat.org/article/PIIS1359646210005397/abstract?rss=yes Three-dimensional dislocation dynamics simulations were employed to examine how hard coatings affect plastic deformation in micron- and submicron-sized, single-crystal pillars (“micropillars”) of nickel. Cross-slip of dislocations in the coated samples was found to be necessary for the formation of banded structures and subcells. Our simulations thus offer an explanation for both the significant increases in compressive strength and the higher strain-hardening rate as well as formation of banded structures in coated micropillars. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980725 Tue, 10 Aug 2010 23:00:00 +0100 3980725 http://www.scriptamat.org/article/PIIS1359646210005361/abstract?rss=yes The fatigue strength of Cu–Be alloy with tensile strength ranging from 500 to 1300MPa was optimized by different treatments. The experimental results demonstrate that the optimum fatigue strength of the Cu–Be alloy at 107 cycles is 323MPa, which does not correspond to the material state with the highest tensile strength. It is indicated that improving the tensile strength cannot always achieve the optimum fatigue strength. The relations between fatigue strength and other mechanical properties are discussed. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980722 Tue, 10 Aug 2010 23:00:00 +0100 3980722 http://www.scriptamat.org/article/PIIS1359646210005373/abstract?rss=yes The jerky flow for a Zr-based bulk metallic glass is analyzed, based on the accumulation and dissipation of the elastic energy, and the temperature rise within the shear bands. The formation of a viscous layer results in the tiny disturbance among the jerky flows, which makes the jerky-flow kinetics inhomogeneous. The parameter, the jerky-drop-stressing speed, is used to characterize the shear-banding kinetics. An increased shear-banding speed dominates upon loading, which is in agreement with the change of the free volume. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980721 Tue, 10 Aug 2010 23:00:00 +0100 3980721 http://www.scriptamat.org/article/PIIS135964621000535X/abstract?rss=yes The low-cycle tension–tension fatigue properties of extruded Mg–3%Al–1%Zn alloy plate have significantly different features in twinning-dominated samples and dislocation-dominated samples. The twinning-dominated samples show more pronounced cyclic hardening and longer fatigue life than those of the slip-dominated samples. The elongated lifetime of the twinning-dominated samples may be due to the roughness-induced crack closure. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980720 Tue, 10 Aug 2010 23:00:00 +0100 3980720 http://www.scriptamat.org/article/PIIS1359646210005348/abstract?rss=yes Direct measurement and quantification of phase transformation in a low-alloyed transformation induced plasticity steels depending on the tensile load as well as determination of the real true stress and true strain values were carried out in-situ using high energy synchrotron radiation. Digital image correlation technique was used to quantify more precisely the true strain values. The aim of the work was to obtain a better understanding of the phase transformation of commercial low-alloyed transformation induced plasticity steel depending on the true strain and true stress values. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044966 Sun, 08 Aug 2010 23:00:00 +0100 4044966 http://www.scriptamat.org/article/PIIS1359646210005336/abstract?rss=yes The deformation mode of polycrystalline Co–27Cr–5Mo (in mass%) alloy consisting of the hexagonal close-packed ε phase was examined. Basal 〈a〉 and prismatic 〈a〉 slips were the dominant deformation modes. The activation of these 〈a〉 slips is strongly dependent on Schmid factor, which indicates that the values of critical resolved shear stress for basal 〈a〉 slip and prismatic 〈a〉 slip are similar. For tensile strains up to 10%, the frequent occurrence of deformation twins could not be confirmed by electron backscattered diffraction analysis. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980724 Sun, 08 Aug 2010 23:00:00 +0100 3980724 http://www.scriptamat.org/article/PIIS1359646210005324/abstract?rss=yes The drag effect by second-phase particles on grain boundary motion is considered with regard to the triple line particle–grain boundary that is formed during the interaction between a particle and a grain boundary. A quantitative analysis of this effect has become possible due to recent measurements of the triple line energy. In the limit of large particles (dp>50nm) the particle is wet by the boundary (Zener approximation) whereas smaller particles are repelled by the grain boundary. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980723 Sun, 08 Aug 2010 23:00:00 +0100 3980723 http://www.scriptamat.org/article/PIIS1359646210005294/abstract?rss=yes Based on first-principles calculations, we present a study for p-type ZnO doping. We find that N-B complex cannot realize p-type ZnO because N-B forms a fully passive complex, while N-B-VZn complex is demonstrated as having a weak p-type conductivity under O-rich conditions. Interestingly, we further find that 3N-B complex is a stable acceptor that has shallower transition level and lower formation energy under Zn-rich conditions. We expect this study to be helpful in synthesizing good p-type ZnO by controlling (N,B) codoping. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980718 Sun, 08 Aug 2010 23:00:00 +0100 3980718 http://www.scriptamat.org/article/PIIS1359646210005300/abstract?rss=yes Correlations between spall damage and local microstructure were investigated using polycrystalline copper samples via laser-driven plate impacts at low pressures. Electron backscattering diffraction was used to relate the presence of porosity to microstructural features such as grain boundaries and triple points. Preferred void-nucleation sites were identified in terms of their crystallography via statistical sampling in serial sectioned specimens. Results indicate that terminated twins and grain boundaries with misorientations between 25° and 50° are the preferred locations for intergranular damage localization. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980717 Sun, 08 Aug 2010 23:00:00 +0100 3980717 http://www.scriptamat.org/article/PIIS1359646210005282/abstract?rss=yes The precipitation process in Al–Zn–Mg-based alloys has been revisited using high-resolution transmission electron microscopy. It was found that there is an intermediate phase between the η′ phase and the η phase. This intermediate phase with a hexagonal structure can be termed the η precursor, since its a lattice parameter is the same as that of the η′ phase and its c lattice parameter is approximately the same as that of the η phase. Transformation from the η′ phase to the η phase occurs smoothly with this η precursor existing between them. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980716 Sun, 08 Aug 2010 23:00:00 +0100 3980716 http://www.scriptamat.org/article/PIIS1359646210004641/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831248 Sat, 07 Aug 2010 08:21:29 +0100 3831248 http://www.scriptamat.org/article/PIIS1359646210005178/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831247 Sat, 07 Aug 2010 08:21:29 +0100 3831247 http://www.scriptamat.org/article/PIIS1359646210005270/abstract?rss=yes It has been suggested in recent work that the observed spread in crystallographic orientations of martensite can be explained in terms of a new theory which attributes the effect to crystals which are at different stages in the evolution of martensite. We show here that this is mathematically incorrect and that the theory does not make predictions. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4097725 Thu, 05 Aug 2010 23:00:00 +0100 4097725 http://www.scriptamat.org/article/PIIS1359646210005233/abstract?rss=yes Spherical or branch-like architectures assembled from Ni nanocones have been synthesized. Micromagnetic simulation of a single Ni nanocone reveals that it has a unique magnetization structure with a vortex structure at the bottom and a uniform structure at the top. Two resonance peaks at 4.4 and 12.0GHz appear in the high-frequency magnetic spectrum. The complex permittivity is very low in the frequency range 1–18GHz, which makes the magnetic permeability and the permittivity match well and benefits the microwave absorption. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044965 Sun, 01 Aug 2010 23:00:00 +0100 4044965 http://www.scriptamat.org/article/PIIS1359646210005245/abstract?rss=yes The deformation behavior of a nanograined/ultrafine-grained (NG/UFG) austenitic stainless steel characterized by high strength–high ductility combination is investigated via nanoindentation and electron microscopy, and the behavior compared with its coarse-grained (CG) counterpart. In NG/UFG steel, mechanical twinning was an active deformation mechanism, while in CG steel, nucleation of strain-induced martensite at the shear bands occurred. The differences in deformation mechanisms of NG/UFG and CG steels are reflected in the discrete burst in the force–displacement plots and attributed to austenite stability. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980715 Sun, 01 Aug 2010 23:00:00 +0100 3980715 http://www.scriptamat.org/article/PIIS1359646210005257/abstract?rss=yes The effect of a very short aging treatment (360s at 873K) on the superelastic properties has been investigated on the ternary Ti–20Nb–6Zr (at.%) titanium-based alloy. Such short thermal treatment is shown to be an efficient way to obtain a recrystallized microstructure with ultrafine β grains of about 1–2μm. In addition, the associated mechanical properties display an outstanding improvement in superelastic properties, with 3.2% of elastic recovery combined with high tensile strength of around 750MPa. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980714 Sun, 01 Aug 2010 23:00:00 +0100 3980714 http://www.scriptamat.org/article/PIIS1359646210005002/abstract?rss=yes We have shown that 1MeV Ni+ ion irradiation can cause nanocrystal formation in Ni52.5Nb10Zr15Ti15Pt7.5 metallic glass (MG). The process requires precipitate formation and subsequent crystal growth within the precipitates. Temperature evolution modeling of damage cascades suggests a locally melted region within the damage cascade with substantial temperature gradients and rapid energy dissipation, with a quenching rate much larger than MG’s critical cooling rate. Thus, the damage cascade regions do not directly develop nanocrystals. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980712 Sun, 01 Aug 2010 23:00:00 +0100 3980712 http://www.scriptamat.org/article/PIIS1359646210005129/abstract?rss=yes The effect of hydrogen on dislocation nucleation in a vanadium (100) single crystal has been examined by means of nanoindentation. For electrochemically doped samples to different hydrogen concentrations within the α-phase, the pop-in load decreased with the increase in hydrogen concentration and multiple pop-ins were observed on the load–displacement curves. The interaction between the dissolved hydrogen atoms and the newly formed dislocation loops, resulting in the reduction of their line energy, is evaluated and explained based on the novel thermodynamic defactant concept. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933020 Sun, 01 Aug 2010 23:00:00 +0100 3933020 http://www.scriptamat.org/article/PIIS1359646210005099/abstract?rss=yes The effect of aging on the deformation behavior of austenitic Fe–28Mn–9Al–0.8C steel has been investigated. Various aging conditions were used to alter the size and volume fraction of κ-carbide precipitates. It is shown that the presence of nanosized κ-carbide precipitates, even in as-solutionized specimen, results in the formation of planar slip bands as a major deformation mode. The change in work-hardening rate with aging time is explained by the change in the activity of slip band formation with aging time. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933019 Sun, 01 Aug 2010 23:00:00 +0100 3933019 http://www.scriptamat.org/article/PIIS1359646210005117/abstract?rss=yes The microstructure and mechanical properties of extruded Mg–1.0Zn–0.5Ca alloys were studied. Observation of the microstructure indicates that the addition of Ca tends to weaken the extrusion texture. The results of tensile tests show that the alloy extruded at 643K exhibits remarkable elongation of 44% allied with strength of 215MPa. Moreover, the strength of the alloy extruded at 583K is increased to 300MPa. These superior properties can be attributed to grain refinement and the unique extrusion texture. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933018 Sun, 01 Aug 2010 23:00:00 +0100 3933018 http://www.scriptamat.org/article/PIIS1359646210005105/abstract?rss=yes The glass-to-liquid transition was evaluated by in situ transmission electron microscope observation of crystalline Cu globule aggregation in Fe–Zr–B amorphous or supercooled liquid matrices in Fe50Zr10B20Cu20 melt-spun ribbon. Globule aggregation was not observed near the critical glass transition temperature, but was observed near the glass transition temperature evaluated by conventional differential scanning calorimetry measurements. The viscosity of Fe–Zr–B-based metallic glass may decrease during the glass-to-liquid transition, and a polygonal crystalline phase may form by Cu globule aggregation. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933017 Sun, 01 Aug 2010 23:00:00 +0100 3933017 http://www.scriptamat.org/article/PIIS1359646210005075/abstract?rss=yes We investigate elastic energy-driven grain boundary migration in a strained copper bicrystal using an atomistically informed phase field model. In a bicrystal experiencing a uniform strain, the softer grain has a lower energy density and grows at the expense of the harder grain. In a bicrystal experiencing heterogeneous strain, the softer grain has a higher energy density, yet it still grows. Our findings suggest that the softer grain will grow, irrespective of the difference in the energy densities. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980713 Thu, 29 Jul 2010 23:00:00 +0100 3980713 http://www.scriptamat.org/article/PIIS1359646210005087/abstract?rss=yes The Dillamore orientation, {4411}〈11118〉, which is calculated by the full constraints Taylor model (, with the subscripts 1, 2, and 3 indicating the rolling, transverse, and normal directions, respectively) is stable under plane-strain compression of face-centered cubic (fcc) metals. However, the Dillamore component has been little reported in rolling textures of fcc metals. The component has been observed along with the generally observed Goss {110}〈001〉, brass {110}〈112〉, copper {112}〈111〉, and S {123}〈634〉 components in the texture of 80% rolled copper sheet. The texture was measured by electron backscatter diffraction. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933016 Thu, 29 Jul 2010 23:00:00 +0100 3933016 http://www.scriptamat.org/article/PIIS1359646210005014/abstract?rss=yes In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α→κ′ phase transformation occurred in the alumina under 100keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ′-alumina. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933015 Tue, 27 Jul 2010 23:00:00 +0100 3933015 http://www.scriptamat.org/article/PIIS1359646210004999/abstract?rss=yes We present the stress-induced synthesis of aluminum nanowires having almost perfect crystallinity. Their resistivity is comparable to the lowest bulk value of aluminum, and thus unprecedentedly smaller than the ones observed in other metal nanostructures. We analyze the measured resistivity using the standard theory of scattering in metal wires, and the observed resistivity values are consistent with the infinite average grain size. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933014 Tue, 27 Jul 2010 23:00:00 +0100 3933014 http://www.scriptamat.org/article/PIIS1359646210004987/abstract?rss=yes Nanoporous gold (NPG) is of interest due to its very high surface area to volume ratio. The fabrication of crack-free blanket NPG thin films on silicon substrates using standard clean room methods is reported. Ag–Au precursor alloys are deposited both by thermal vapor deposition as well as by sputter deposition. Dealloying is performed using two different electrochemical regimens, one with a stepped potential increase and the other with a ramped increase. The ramped increase gives better NPG film uniformity. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933013 Tue, 27 Jul 2010 23:00:00 +0100 3933013 http://www.scriptamat.org/article/PIIS1359646210005063/abstract?rss=yes Ti–30Ni–20Cu (at.%) alloy ribbons with an average grain size of 0.25–0.28μm were obtained by applying two-step annealing, comprising a first annealing step at 773–823K and a second annealing step at 748K, to amorphous melt-spun ribbons, which was very small compared with ribbons obtained by one-step annealing at 748–823K (0.64–1.20μm). Hysteresis and elongation associated with the B2–B19 transformation were decreased by two-step annealing, while the fracture stress and strain increased. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933012 Tue, 27 Jul 2010 23:00:00 +0100 3933012 http://www.scriptamat.org/article/PIIS135964621000504X/abstract?rss=yes The rate sensitivity of hexagonal close-packed nanocrystalline Ru films was investigated by nanoindentation, which is found to be a function not only of grain size but also of indentation depth. The enhanced magnitude of the sensitivity is comparable to that of face-centered cubic nanocrystalline metals. Experimental results suggest that the interaction of dislocations with grain boundaries (GBs) and the diffusion along the tip–sample interface are the dominant mechanisms, whereas both GB sliding and Coble creep are ruled out as the rate-controlling deformations. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933010 Tue, 27 Jul 2010 23:00:00 +0100 3933010 http://www.scriptamat.org/article/PIIS1359646210005038/abstract?rss=yes A thermokinetic description was performed for nanoscale grain growth by analyzing the effect of grain boundary (GB) segregation on the initial GB excess amount, Γb. Compared with the model assuming a linear relation between Γb and grain size (i.e. Γb (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933009 Tue, 27 Jul 2010 23:00:00 +0100 3933009 http://www.scriptamat.org/article/PIIS1359646210005026/abstract?rss=yes High strain rate rolling (HSRR) was successfully used to produce ultrafine-grained ZK60 magnesium alloy sheets with superior mechanical properties. The achievement of HSRR is attributed to the preferred initiation of twinning and the subsequent dynamic recrystallization (DRX) to inhibit competitive crack initiation. The microstructural homogeneity is improved as the strain rate rises. High strength and ductility of the HSRRed sheet result from the effects of the refined grains and the low dislocation and twinning densities caused by DRX. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933008 Tue, 27 Jul 2010 23:00:00 +0100 3933008 http://www.scriptamat.org/article/PIIS1359646210004938/abstract?rss=yes The kinetics of the polymorphic C36⇄C14 Laves phase transformation of TiCr2 close to the equilibrium transformation temperature of about 1550K was investigated by differential thermal analysis. Plastic deformation-induced by compression has a considerable affect on the transformation kinetics. This is ascribed to the presence of synchro(-Shockley partial) dislocations introduced during compression. The transformation kinetics are shown to vary with the degree of plastic deformation, i.e. with the dislocation density as characterised by the extent of (X-ray) diffraction line broadening. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980711 Sun, 25 Jul 2010 23:00:00 +0100 3980711 http://www.scriptamat.org/article/PIIS1359646210004975/abstract?rss=yes were investigated by means of scratch tests along [110] and [100] crystallographic directions. It was found that fracture (partial cone cracks) starts along favoured {110} and {111} cleavage planes, with crack orientation varying upon the scratching direction. Moreover, the [100] direction was found to be twice as reliable as the [110] direction. Stress and phase analyses were carried out to explain this effect, which has implications for the design of silicon-based devices. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933011 Sun, 25 Jul 2010 23:00:00 +0100 3933011 http://www.scriptamat.org/article/PIIS1359646210004963/abstract?rss=yes Compressibility of periodically twinned silicon carbide nanowires is studied using in situ high pressure X-ray diffraction. Twinned SiC nanowires displayed a bulk modulus of 316GPa, ∼20–40% higher than previously reported values for SiC of other morphologies. This finding provides direct evidence of a significant effect of twinned structures on the elastic properties of SiC on the nano scale and supports previous molecular dynamics simulations of twin boundary/stacking fault-induced strengthening. Both experiments and simulations indicate that nanoscale twinning is an effective pathway by which to tailor the mechanical properties of nanostructures. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933007 Sun, 25 Jul 2010 23:00:00 +0100 3933007 http://www.scriptamat.org/article/PIIS1359646210004914/abstract?rss=yes Nanostructured NiTi with a graded surface nanostructure was produced by surface mechanical attrition treatment (SMAT). Nanoindentation measurements revealed that the elastic modulus of SMAT samples increased significantly with decreasing distance from the SMAT surface and grain size, reaching ∼85GPa for a grain size of ∼6nm at the surface. This grain size dependence of the elastic modulus was found to be due to suppression of the stress-induced martensitic transformation in nanostructured NiTi. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933006 Sun, 25 Jul 2010 23:00:00 +0100 3933006 http://www.scriptamat.org/article/PIIS135964621000494X/abstract?rss=yes In situ tensile tests have been carried out during X-ray microtomography imaging of dual phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained three-dimensional images. The Argon criterion of decohesion has been used in a model for nucleation in the case where martensite plays the role of inclusions. This criterion has been modified to include the local stress field and the effect of kinematic hardening present in such a heterogeneous material. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933005 Sun, 25 Jul 2010 23:00:00 +0100 3933005 http://www.scriptamat.org/article/PIIS1359646210004926/abstract?rss=yes Scanning transmission electron microscopy and energy dispersive X-ray spectroscopy have been utilized to investigate the distribution of Re in a single crystal nickel-based superalloy. Two types of distributions of element Re have been found near interfaces after creep tests, one in the γ phases, the other near dislocation cores. Re enrichment near dislocation cores is considered to strengthen the high-temperature performance of superalloys by hindering dislocation movement. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933004 Sun, 25 Jul 2010 23:00:00 +0100 3933004 http://www.scriptamat.org/article/PIIS1359646210004367/abstract?rss=yes The authors regret the misspelling of the third authors’ name, which is now corrected above. This typographical error does not change neither the main findings in the paper nor the contributions of the authors. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831276 Sun, 25 Jul 2010 23:00:00 +0100 3831276 http://www.scriptamat.org/article/PIIS1359646210004574/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3784114 Sat, 24 Jul 2010 08:06:27 +0100 3784114 http://www.scriptamat.org/article/PIIS1359646210004720/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3784113 Sat, 24 Jul 2010 08:06:27 +0100 3784113 http://www.scriptamat.org/article/PIIS1359646210004902/abstract?rss=yes Fine Cu interconnects possess small grains that increase the electrical resistivity of the interconnects. We have performed an extensive transmission electron microscopy study of the grain growth in lines of different sizes, using a recently developed automated indexing method. Different annealing processes were conducted, some with the presence of a top layer that possesses very large grains. Quantification (by crystallographic indexation and mapping) of grain growth in lines as narrow as 80nm was achieved. We found that grain growth is clearly impeded by geometrical constraints. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933003 Thu, 22 Jul 2010 23:00:00 +0100 3933003 http://www.scriptamat.org/article/PIIS1359646210004872/abstract?rss=yes Fe–Mn–C and Fe–Mn–Si–Al TWIP steels deformed under the same conditions exhibit different work-hardening rates. The present study investigates the microstructure of plastically deformed Fe–Mn–C and Fe–Mn–Si–Al samples, particularly the internal structure of the mechanically generated twins and their topology at the grain scale. Twins in the Fe–Mn–C steel are finer and full of sessile dislocations, rendering this material distinctly stronger with an improved work-hardening rate. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933002 Mon, 19 Jul 2010 23:00:00 +0100 3933002 http://www.scriptamat.org/article/PIIS1359646210004665/abstract?rss=yes Ultrafine-grained Al alloys produced by high-pressure torsion are found to exhibit a very high strength, considerably exceeding the Hall–Petch predictions for ultrafine grains. This phenomenon can be attributed to the unique combination of ultrafine structure and deformation-induced segregations of solute elements along grain boundaries, which may affect the emission and mobility of intragranular dislocations. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895758 Mon, 19 Jul 2010 23:00:00 +0100 3895758 http://www.scriptamat.org/article/PIIS1359646210004677/abstract?rss=yes The thermal stability and mechanical behavior of LIGA Ni–W alloys with 5 and 15at.% W were investigated. The strength of these alloys exceeds that of pure LIGA Ni, and the underlying microstructures of the Ni–W alloys are stable to 700°C. The Ni–W alloys are brittle as-deposited, but annealed samples exhibited a promising balance of strength and ductility. W-alloyed LIGA Ni offers increased thermal stability and strength, as well as opportunities for tailoring mechanical properties with heat treatment. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=4044964 Wed, 14 Jul 2010 23:00:00 +0100 4044964 http://www.scriptamat.org/article/PIIS1359646210004653/abstract?rss=yes A thermodynamic explanation was recently proposed for the formation of massive layers of cementite without any graphite by gas carburization of steels at 550°C if the gas contains NH3. That explanation is now criticized. It is proposed that a kinetic factor, based on the difficulty of precipitating graphite inside a solid matrix, may contribute to the inhibition of metal dusting in the presence of NH3. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3980710 Wed, 14 Jul 2010 23:00:00 +0100 3980710 http://www.scriptamat.org/article/PIIS1359646210004434/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3746602 Tue, 13 Jul 2010 08:07:47 +0100 3746602 http://www.scriptamat.org/article/PIIS135964621000463X/abstract?rss=yes Taking shear-induced dilatation into consideration in shear transformation zone (STZ) operations, we derive a new yield criterion that reflects the pressure sensitivity in plastic flow in metallic glasses (MGs), which agrees well with experiments. Furthermore, an intrinsic theoretical correlation between the pressure sensitivity coefficient and the dilatation factor is revealed. It is found that the pressure sensitivity of plastic flow of MGs originates in the dilatation of microscale STZs. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895757 Sun, 11 Jul 2010 23:00:00 +0100 3895757 http://www.scriptamat.org/article/PIIS1359646210004616/abstract?rss=yes Commercial Ti with a multimodal grain structure was successfully produced using cryorolling, followed by low-temperature annealing. This multimodal grain structure Ti exhibited a combination of high yield strength (926MPa), a uniform elongation of 11% and a failure elongation of 23%. The strength enhancement was mainly derived from the ultrafine equiaxed grains, while the improved ductility originated from the large fraction of high-angle grain boundaries and the multimodal grain structure. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895756 Sun, 11 Jul 2010 23:00:00 +0100 3895756 http://www.scriptamat.org/article/PIIS1359646210004598/abstract?rss=yes Titanium nanopowders covered with organics which have never been obtained by any previous methods are prepared by pulsed wire discharge (PWD) using titanium wires in helium gas with oleic acid vapor/mist. The prepared titanium particles covered with titanium oleate had not oxidized 1month after preparation at room temperature in air. From these results, we conclude that the preparation of titanium nanopowder with an oxidation-resistant coating of titanium oleate can be successfully achieved by PWD in oleic acid/vapor mist. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895755 Sun, 11 Jul 2010 23:00:00 +0100 3895755 http://www.scriptamat.org/article/PIIS1359646210004586/abstract?rss=yes Ag nanowhiskers were grown on a C-coated Si substrate at 800°C and subsequently coated with Au by physical vapor deposition. The Au forms a single crystalline, epitaxial layer on the nanowhisker and a polycrystalline Au film on the substrate surface. Annealing at 150°C for 70h activates diffusion of Ag into the Au grain boundaries of the polycrystalline film, emptying the Ag nanowhisker core. The remaining epitaxial Au film forms the single crystalline wall of Au(Ag) nanotubes. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895754 Sun, 11 Jul 2010 23:00:00 +0100 3895754 http://www.scriptamat.org/article/PIIS1359646210004604/abstract?rss=yes The stability of model nanostructured Cu90Mo10 and Cu90W10 alloys during irradiation with 1.8MeV Kr+ at very high temperatures was investigated. Significant coarsening occurs only above ∼0.6Tm in Cu90Mo10 and ∼0.8Tm in Cu90W10 (Tm is the melting point of Cu). Below these temperatures, nanoprecipitates nucleate and grow to a saturation diameter of ∼4nm. These very small nanoprecipitates confer remarkable microstructural stability, with the Cu grain size remaining below 40nm. Computer simulations help to explain why these nanostructures are so stable. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895753 Sun, 11 Jul 2010 23:00:00 +0100 3895753 http://www.scriptamat.org/article/PIIS1359646210004628/abstract?rss=yes We present the electric and magnetic properties of nanostructured Pb0.7Sr0.3(Fe0.012Ti0.988)O3 (PSFT3) thin film. The magnetoelectric coupling has been studied by polarization hysteresis loops under the influence of an applied magnetic field and a phase transition anomaly. At room temperature PSFT3 film shows diffuse phase transition of dielectric diffusivity (γ=1.94). The Vogel–Fulcher (VF) relation implies the relaxor characteristics of the film by extracting the VF freezing temperature and the activation energy of polar nanoregions. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831273 Sun, 11 Jul 2010 23:00:00 +0100 3831273 http://www.scriptamat.org/article/PIIS1359646210004549/abstract?rss=yes High-resolution electron backscatter diffraction was employed to establish the microstructural stability in severely cryodeformed copper during long-term static storage at room temperature. The material was shown to exhibit grain growth including some aspects of abnormal grain growth. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895751 Thu, 08 Jul 2010 23:00:00 +0100 3895751 http://www.scriptamat.org/article/PIIS1359646210004562/abstract?rss=yes Effects of Ru on the compressive creep of Ni-based single-crystal superalloys were investigated at 750 and 900°C. The addition of Ru improved the creep strength at 750°C. It enhanced the dissociation of dislocations in the matrix channels and would inhibit the nucleation of the a〈112〉 dislocation ribbons which shear the matrix and the precipitates; as a result, the mechanical-twin formation was also impeded and creep strength was increased. However, Ru addition did not improve creep strength at 900°C. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895748 Thu, 08 Jul 2010 23:00:00 +0100 3895748 http://www.scriptamat.org/article/PIIS1359646210004495/abstract?rss=yes The family of half-metallic ferromagnets Co2TiZ exhibits exceptional transport properties. The investigated compounds Co2TiAl(1−x)Six (x=0.25, 0.5, 0.75) show Curie temperatures (TCs) that vary between 250 and 350K, depending on the composition. Above TC the Seebeck coefficient remains constant. This makes them promising candidates for thermoelectric devices such as thermocouples with a tunable working range. The electrical resistivity data show an anomaly at TC which is attributed to changes in the electronic structure and therefore in the carrier concentration. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895752 Wed, 07 Jul 2010 23:00:00 +0100 3895752 http://www.scriptamat.org/article/PIIS1359646210004379/abstract?rss=yes The atomic structure of Zr70Ni30−xPdx (x=0–30) amorphous alloys (AAs) was systematically investigated via synchrotron radiation-based experiments and simulations. A relatively short Zr–Pd bond was detected in Zr70Pd30, which is attributed to the strong interaction between Zr and Pd “soft” atoms. This phenomenon was further explained by performing electronic interaction calculations upon some Voronoi clusters in the ZrPd sample and clusters extracted from the corresponding crystal phases. We suggest that soft atoms may have a significant impact on the internal structure in some metal–metal AAs. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831271 Wed, 07 Jul 2010 23:00:00 +0100 3831271 http://www.scriptamat.org/article/PIIS1359646210004537/abstract?rss=yes Sn–37Pb solder and pure Sn metal exhibit a conspicuous high-temperature damping background (HTDB) in low-frequency internal friction curves with activation energies, H, of HTDB being 0.43 and 0.98eV, respectively. Sn–37Pb solder has a lamellar eutectic structure that can promote the diffusion-assisted climb of dislocations, resulting in lower H. Sn–3Ag–0.5Cu solder shows no HTDB in curves since the formation of Cu6Sn5 and Ag3Sn intermetallics in the eutectic network band can impede dislocation motion. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933001 Tue, 06 Jul 2010 23:00:00 +0100 3933001 http://www.scriptamat.org/article/PIIS1359646210004525/abstract?rss=yes The Haasen plot (inverse activation area 1/Δa vs. offset flow stress σ–σs) for solute-strengthened alloys is usually assumed additive, 1/Δa=1/Δas+1/Δaf, with 1/Δaf∼β(σ–σs) due to forest interactions. Experiments often show a slope (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895750 Tue, 06 Jul 2010 23:00:00 +0100 3895750 http://www.scriptamat.org/article/PIIS1359646210004550/abstract?rss=yes Strain rate sensitivity measurements are used to identify twinning and changes in deformation mechanisms in a Mg AZ31 alloy over a wide range of temperatures and grain sizes. At low temperatures, there is significant twinning at low strains with strain-rate insensitivity; at large strains, strain rate sensitivity is noted, corresponding to deformation by multiple slip. At high temperatures, there is very little twinning and this leads to a significant strain rate sensitivity from the early stages of deformation. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895749 Tue, 06 Jul 2010 23:00:00 +0100 3895749 http://www.scriptamat.org/article/PIIS1359646210004501/abstract?rss=yes The tensile creep performance of Mg–Sn alloys, containing Zn and Zn+Na alloying additions, have been measured at temperatures of 177 and 150°C. Under a load of 60MPa, the Mg–Sn–Zn–Na alloy shows secondary creep rates five orders of magnitude slower than the binary alloy and approximately three orders of magnitude slower than the ternary Mg–Sn–Zn alloy. Transmission electron microscopy shows that the origin of the excellent creep properties of the Mg–Sn–Zn–Na alloy is the remarkable thermal stability of the precipitate structure. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831275 Tue, 06 Jul 2010 23:00:00 +0100 3831275 http://www.scriptamat.org/article/PIIS1359646210004513/abstract?rss=yes The detection and quantification of small quantities of Cr in (La,Sr)MnO3/Y–ZrO2 solid oxide fuel cell (SOFC) cathodes by energy-dispersive X-ray spectroscopy (EDXS) is not straightforward as Cr X-ray emission lines overlap with La/Mn and O lines. This work proposes an empirical law correlating the La peak height ratio Lβ2.15/Lα1 to Cr concentrations determined on Cr-doped LSM–YSZ samples characterized by EDXS. Calibration for the law was obtained by chemical analysis of dissolved cathodes. Quantification was confirmed by wavelength-dispersive X-ray spectroscopy. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831274 Tue, 06 Jul 2010 23:00:00 +0100 3831274 http://www.scriptamat.org/article/PIIS1359646210004380/abstract?rss=yes ZrC–ZrB2 matrix composites were prepared by reactive hot pressing at 1900°C using ZrC and LaB6 as raw materials. A new layered phase was found, which made the fracture toughness of composites enhanced significantly. The incorporation of SiC further improved fracture toughness and flexural strength of the composites. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831272 Tue, 06 Jul 2010 23:00:00 +0100 3831272 http://www.scriptamat.org/article/PIIS1359646210004343/abstract?rss=yes Interface delamination in metal–rubber-type stretchable electronic systems leads to early failure. This paper reports an investigation of metal–rubber interfaces through in situ scanning electron microscopy imaging of the progressing delamination front of 90° peel tests of rubber on copper samples. The results show that the energy dissipated in the forming, elongation and rupture of ∼50μm long fibrils constitutes the major part of the work of separation. The experiments are characterized and modeled using a cohesive zone-enriched finite-element model. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831269 Sun, 04 Jul 2010 23:00:00 +0100 3831269 http://www.scriptamat.org/article/PIIS1359646210004355/abstract?rss=yes The atomic structure of Zr48Cu45Al7 bulk metallic glass is investigated by Monte Carlo simulation upon synchrotron radiation data. Strong bonding and dense cluster packing caused by the minor addition of Al are two key local structural features that may retard the rearrangement of atoms and clusters during quench, facilitating glass formation. Based on this work, we present a strategy to reveal the relationship between local structure and glass-forming ability by focusing on the structural features caused by doping atoms from the atomic and cluster scales. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831270 Thu, 01 Jul 2010 23:00:00 +0100 3831270 http://www.scriptamat.org/article/PIIS1359646210004331/abstract?rss=yes The energy of 388 grain boundaries in Al, Au, Cu and Ni were calculated using atomistic simulations. Grain boundary energies in different elements are strongly correlated. Consistent with a dislocation model for grain boundary structure, the boundary energy scales with the shear modulus. Boundaries with substantial stacking fault character scale with the stacking fault energy. There is more scatter in the data for Al, which has a high stacking fault energy, than for the low stacking fault energy elements. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3895747 Sun, 27 Jun 2010 23:00:00 +0100 3895747 http://www.scriptamat.org/article/PIIS135964621000432X/abstract?rss=yes Compared to its mechanical behavior at 298K, the fracture strain of a Cu46Zr46Al8 bulk-metallic glass is slightly increased, but the maximum strength is distinctly increased by 13.3% at 77K. At 77K, the serrations in the stress–strain curve disappear. Based on the calculation of the temperature rise within the shear bands and the heat conduction in the heat-affected zones, the large and instantaneous temperature rise and the rapid heat conduction are responsible for the disappearance of serrations upon shear banding. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831268 Sun, 27 Jun 2010 23:00:00 +0100 3831268 http://www.scriptamat.org/article/PIIS1359646210004306/abstract?rss=yes Nanostructured α-Ta films were sputtered at room temperature in order to synthesize material that had either compressive or tensile stress states (−1500 to 1000GPa). The films were coated by magnetron sputtering at various pressures using Si substrates with and without an α-Ta underlayer. The roles of the substrate/film interface, underlayer, grain size and film texture were also investigated as a function of sputtering conditions and residual stress. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831267 Sun, 27 Jun 2010 23:00:00 +0100 3831267 http://www.scriptamat.org/article/PIIS1359646210004318/abstract?rss=yes During tensile testing of pseudoelastic NiTi, martensitic transformation bands propagate through the specimen. We compare stress–strain curves for different gauge lengths and cross-head displacement rates (CHDRs) to demonstrate that the CHDR is a physically meaningful measure that unambiguously characterizes the thermomechanical loading situation. This allows estimation of local strain rates, which are determined for the first time by considering the finite width of mesoscale phase interfaces. Local rates and macroscopic strain rates differ by at least one order of magnitude. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831266 Sun, 27 Jun 2010 23:00:00 +0100 3831266 http://www.scriptamat.org/article/PIIS1359646210004288/abstract?rss=yes The present investigation was conducted to study vacuum brazing between carbon–carbon composites (CC) and TiAl alloys with Ag–Cu–Ti filler metal. The mutual exclusion between the Ag and Ti elements had a significant influence on the joint microstructure. The isothermal solidification of the Ag-based solid solution led to a layered microstructure, which was beneficial to the joining strength. A new method of making holes in the CC composite surface was introduced, and the joint was strengthened by the infiltration of filler metals into these holes. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831265 Sun, 27 Jun 2010 23:00:00 +0100 3831265 http://www.scriptamat.org/article/PIIS1359646210004161/abstract?rss=yes (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3695456 Fri, 25 Jun 2010 08:04:23 +0100 3695456 http://www.scriptamat.org/article/PIIS135964621000429X/abstract?rss=yes We demonstrate two Sb-based alloys, Ga25Te8Sb67 and Ga18Te12Sb70, that have a crystallization temperature above 245°C and activation energy of crystallization greater than 5eV, for phase-change memory application. The temperature for 10year data retention reaches 183 and 210°C for Ga18Te12Sb70 and Ga25Te8Sb67, respectively. Test cells made of alloy Ga25Te8Sb67 show similar memory switching behavior at pulse widths of 500–20ns. Compared with the benchmark chalcogenide Ge2Sb2Te5, the two antimonide alloys possess much improved thermal stability for applications in phase-change memory. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831264 Thu, 24 Jun 2010 23:00:00 +0100 3831264 http://www.scriptamat.org/article/PIIS1359646210004252/abstract?rss=yes Friction stir lap-welded advanced high-strength M190 steel exhibited formation of lath martensite at weld nuggets, a ferrite layer at faying surfaces and a ferrite–pearlite microstructure at the bottom of the stir zone. The phase transformation was governed by severe plastic deformation in the austenitic region followed by cooling. The strain rate and peak temperature played key roles in controlling the prior-austenitic grain size and were correlated to the Zener–Hollomon parameter. An empirical relationship has been obtained for dynamically recrystallized austenite grains. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831263 Thu, 24 Jun 2010 23:00:00 +0100 3831263 http://www.scriptamat.org/article/PIIS1359646210004276/abstract?rss=yes Deformation behaviors of monocrystalline Si induced by nanoscratching were systematically investigated by use of cross-sectional transmission electron microscopy and Raman spectroscopy. The study demonstrated that the lateral load in nanoscratching played a key role in the amorphization of Si, which led to a different phase transformation behavior when compared with the well-documented phase transformation route in nanoindentation. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831262 Thu, 24 Jun 2010 23:00:00 +0100 3831262 http://www.scriptamat.org/article/PIIS1359646210004264/abstract?rss=yes The complexities accompanying the interpretation of electron diffraction patterns in the extended Sm–Co alloy system are discussed. The many possibilities of confusing the prominent three phases of the homologous series Smn+1Co5n−1 (n=2,3,4) with each other and with SmCo5 are highlighted, showing the limitations but also the power of this method. The observation of a diffraction pattern that is ostensibly the SmCo5 type does not preclude the possibility that it is actually due to a compound from the series Smn+1Co5n−1. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831261 Thu, 24 Jun 2010 23:00:00 +0100 3831261 http://www.scriptamat.org/article/PIIS1359646210004239/abstract?rss=yes The wear resistance of a bearing steel was investigated using laser surface remelting cooled by water. The weight loss was reduced by over 50% with an overall hardness of ∼1150 HV. An ultrafine microstructure along with nanocarbide was acquired, which generated an accumulative contribution of grain refinement, precipitation strengthening, dislocation strengthening and a mixed microstructure. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831260 Wed, 23 Jun 2010 23:00:00 +0100 3831260 http://www.scriptamat.org/article/PIIS1359646210004240/abstract?rss=yes The combination of ultramicrotomy and low-voltage scanning electron microscopy, with selective detection of backscattered electrons, significantly improved depth and lateral resolutions and atomic number contrast (Z-contrast) sensitivity, enabling high-resolution tomography of localized corrosion. This approach has advanced the understanding of the relationship between the distribution of S-phase particles and the initiation and development of localized corrosion, and the transition to intergranular corrosion in an AA2024-T3 aluminium alloy. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831259 Wed, 23 Jun 2010 23:00:00 +0100 3831259 http://www.scriptamat.org/article/PIIS1359646210004100/abstract?rss=yes We presented detailed characterizations of the ferromagnetic properties of undoped and Cr-doped SnO2 nanowires synthesized by chemical vapor deposition. All the samples exhibit room-temperature ferromagnetism. Our experiments reveal that, in addition to the contribution of surface oxygen vacancies, Cr doping into SnO2 plays an important role in tuning the ferromagnetism of SnO2 nanostructures. Doping the SnO2 nanowires with 1.8at.% Cr enhances the magnetization by 28%. We applied the bound magnetic polaron model to successfully explain the enhancement of ferromagnetism. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3933000 Sun, 20 Jun 2010 23:00:00 +0100 3933000 http://www.scriptamat.org/article/PIIS1359646210004215/abstract?rss=yes We report the enhanced precipitation-hardening response of Mg–0.5Ca (wt.%) alloy by microalloying with Al. The peak hardness of 50 HV for the binary alloy was enhanced to 72 HV in a ternary Mg–0.5Ca–0.3Al alloy. Transmission electron microscopy and 3D atom probe analyses confirmed that the improvement in the peak hardness is associated with the dense precipitation of ordered monolayer Guinier–Preston zones and the subsequent formation of Al2Ca causes the over-aging. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831258 Sun, 20 Jun 2010 23:00:00 +0100 3831258 http://www.scriptamat.org/article/PIIS1359646210004203/abstract?rss=yes An experimental study of deformation twins in a polycrystalline α-Ti bend specimen was performed. In some grain pairs, mechanical twins in adjacent grains were coincident at a grain boundary (T+T). Based on the identified T+T pairs, factors including twin system alignment, twinning Schmid factor, misorientation of the parent grains and parent grain size were assessed. An combination of geometric conditions was identified that can account for the formation of most of the observed T+T pairs. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831257 Sun, 20 Jun 2010 23:00:00 +0100 3831257 http://www.scriptamat.org/article/PIIS1359646210004112/abstract?rss=yes The number of twins formed in a compressed Mg–5wt.% Zn alloy increased when precipitate particles were present, reaching a maximum in the peak-aged condition. Particles were observed to promote twin nucleation, but inhibit twin growth. A simple model has been developed to show that in peak- and over-aged condition the increase in twin number is accurately predicted by assuming the additional stress driving twin nucleation equates to the Orowan stress inhibiting twin growth. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831256 Sun, 20 Jun 2010 23:00:00 +0100 3831256 http://www.scriptamat.org/article/PIIS1359646210004094/abstract?rss=yes The effect of ausforming on kinetics, morphology and crystallography of nanobainite steel was examined by electron backscattered diffraction and transmission electron microscopy. Ausforming has been found to accelerate bainite transformation at 573K. A characteristic microstructure consisting of blocky bainitic laths and retained austenite is observed in the ausformed bainite steel, where strong variant selection takes place due to the operated slip systems. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831255 Sun, 20 Jun 2010 23:00:00 +0100 3831255 http://www.scriptamat.org/article/PIIS1359646210004082/abstract?rss=yes Ultrafine-grained duplex manganese-bearing steels fabricated by quenching and annealing demonstrated excellent combinations of tensile elongation of 31–44% and tensile strength of 1–1.5GPa and a three-stage work-hardening behavior. Their enhanced mechanical properties and work-hardening behavior were explained by their dynamic composition due to the strain induced phase transformation from large-fractioned austenite (>30%). It was suggested that the austenite volume fraction and its mechanical stability is the key to understand the phase transformation induced deformation behavior. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831254 Sun, 20 Jun 2010 23:00:00 +0100 3831254 http://www.scriptamat.org/article/PIIS1359646210004227/abstract?rss=yes Magnesium alloy research and development has expanded tremendously during the past decade, after a period of relatively slow expansion since the 1960s. There are now numerous new applications within the automotive and consumer goods (including cases for portable electronics and hand-held power tools) sectors, and there is currently growing interest in developing new applications within the defense and aerospace sectors. While magnesium alloys have recently received considerable attention and have been intensively researched, there are still many fundamentally and/or technologically important questions to be answered before this class of engineering alloys can find much wider applications. For example, what are the key factors in controlling the strength and creep resistance of magnesium ca... Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3784115 Sun, 20 Jun 2010 23:00:00 +0100 3784115 http://www.scriptamat.org/article/PIIS1359646210004070/abstract?rss=yes Al–Cr surface alloys prepared by injecting Cr powder into the melt pool generated in an Al substrate by a high-powered CO2 laser beam followed by laser remelting present a microstructure consisting of equiaxed cells comprised of extremely fine Al7Cr particles radially distributed in an α-Al matrix. The analysis of this microstructure shows that it originated from solidification. Its morphology is typically eutectic, confirming the existence of the L→α-Al+Al7Cr eutectic reaction predicted by some Al–Cr phase diagram configurations proposed recently. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831253 Thu, 17 Jun 2010 23:00:00 +0100 3831253 http://www.scriptamat.org/article/PIIS1359646210004057/abstract?rss=yes Metastable solid-solution Ti1−xAlxN thin films synthesized by plasma-assisted vapour deposition crystallize in the cubic NaCl structure with AlN mole fractions x⩽0.7. Based on X-ray diffraction and ab initio calculations, we reveal that this critical value only slightly decreases to 0.69 with the addition of up to n=0.125mol fraction NbN to form cubic Ti1−x−nAlxNbnN. During annealing in vacuum to 1450°C, the as-deposited single-phase cubic coatings decompose to form cubic Ti1−nNbnN and wurtzite AlN. (Source: Scripta Materialia) Scripta Materialia journals http://www.medworm.com/rss/comments.php?id=3831252 Thu, 17 Jun 2010 23:00:00 +0100 3831252