Scripta Materialia RSS feed: Current Issue. Scripta Materialia is a LETTERS journal of Acta Materialia , providing a forum for the rapid publication of short communications on the relationship between the structure and the properties of inorganic materials. The emphasis is on originality rather than incremental research. Short reports on the development of materials with novel or substantially improved properties are also welcomed. Emphasis is on either the functional or mechanical behavior of metals, ceramics and semiconductors at all length scales. The following aspects are of particular interest: (i) discovery or development of new materials with novel functional or mechanical properties of potential engineering interests; (ii) characterization of the structure and chemistry of materials for understanding the properties; (iii) cutting-edge experiments and theory for understanding structure-property relationships; (iv) novelty in simulation and modeling in the context of understanding properties, preferably combined with experimental verification; (v) elucidation of the mechanisms involved in the synthesis and processing of materials as a route to the elucidation of properties; In addition, Scripta Materialia publishes comments on papers published in Acta Materialia and Scripta Materialia . The journal also publishes Viewpoint Sets, which are a collection of invited short articles focused on topics of current interest within the scope of the journal and coordinated by invited guest editors.http://www.scriptamat.org/?rss=yesElsevier Inc.en © 2010 Published by Elsevier Inc. All rights reserved. Scripta Materialia1359-6462637October 2010 © 2010 Published by Elsevier Inc. All rights reserved. healthpermissions@elsevier.comhttp://www.scriptamat.org/article/PIIS1359646210004720/abstract?rss=yesEditors for Scripta Materialia10.1016/S1359-6462(10)00472-0Scripta Materialia 63, 7 (2010)2010-10-01Scripta Materialia2010-10-01637S1359-6462(10)X0014-8iiiiiihttp://www.scriptamat.org/article/PIIS1359646210004574/abstract?rss=yesRecipients of the 2009 ACTA Student AwardsSubhash Mahajan10.1016/j.scriptamat.2010.07.006Scripta Materialia 63, 7 (2010)2010-10-01Scripta Materialia2010-10-01637S1359-6462(10)X0014-8669669http://www.scriptamat.org/article/PIIS1359646210004227/abstract?rss=yesMagnesium 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 casting and wrought alloys? What dictates the nucleation and growth of various deformation twins under different loading conditions? How to achieve random orientation, i.e. greatly weakened texture, in wrought magnesium alloys and therefore improve the formability of these alloys? What are the phase equilibria and microstructural constituents in existing and emerging magnesium alloys of technological importance? Therefore, it is timely to assemble this viewpoint set to examine, in a coordinated way, the current status in the following four major areas of research:The goal of this set of viewpoints is provide a perspective which will guide future research aimed at improving the properties and broadening the structural applications of magnesium alloys.Preface to the viewpoint set on: The current state of magnesium alloy science and technologyS.R. Agnew, J.F. Nie10.1016/j.scriptamat.2010.06.029Scripta Materialia 63, 7 (2010)2010-06-21Scripta Materialia2010-06-21637S1359-6462(10)X0014-8Viewpoint set no. 47671673http://www.scriptamat.org/article/PIIS1359646210000461/abstract?rss=yesAbstract: An overview is given on ternary phase diagram data involving magnesium with different rare earths (RE), including the Mg–Y–RE systems. An original thermodynamic description of quaternary Mg–Ce–Gd–Y alloys including the ternary subsystems is developed. Similarities and differences of the phase relations involving magnesium with different RE elements and yttrium are highlighted. The relevance for the impact of different components in mischmetal on the properties of Mg–RE alloys is emphasized.Thermodynamic modeling of the Mg–Ce–Gd–Y systemJoachim Gröbner, Rainer Schmid-Fetzer10.1016/j.scriptamat.2010.01.035Scripta Materialia 63, 7 (2010)2010-01-25Scripta Materialia2010-01-25637S1359-6462(10)X0014-8Viewpoint set no. 47674679http://www.scriptamat.org/article/PIIS1359646209007969/abstract?rss=yesAbstract: In studying the thermodynamics and phase stability of Mg alloys, one is often confronted with the lack of accurate, quantitative experimental data. This deficiency can be partially rectified via first-principles calculations based on density functional theory. In this paper, we will illustrate the utility of first-principles energetics for Mg alloys using three case studies (i) formation energies of ordered/disordered solid phases; (ii) solute–vacancy binding energies in Mg; (iii) point defect formation energies of β-Mg17Al12. These first-principles calculations can provide highly accurate thermodynamic and kinetic information for Mg alloys.First-principles density functional calculations for Mg alloys: A tool to aid in alloy developmentDongwon Shin, Christopher Wolverton10.1016/j.scriptamat.2009.12.032Scripta Materialia 63, 7 (2010)2009-12-23Scripta Materialia2009-12-23637S1359-6462(10)X0014-8Viewpoint set no. 47680685http://www.scriptamat.org/article/PIIS1359646210001958/abstract?rss=yesAbstract: Models for composition and temperature dependencies of single-crystal elastic stiffness coefficients are developed and applied to the Al12Mg17 and hexagonal closed-packed solution phases in the Mg–Al system based on data from first-principles calculations. In combination with models for multi-phases, the bulk, shear, and Young’s moduli of Mg–Al alloys are predicted and compared with available experimental data in the literature. It is noted that both phase transition and grain boundary sliding may play important roles in the elastic coefficients as a function of temperature.Computational modeling of effects of alloying elements on elastic coefficientsZ.K. Liu, H. Zhang, S. Ganeshan, Y. Wang, S.N. Mathaudhu10.1016/j.scriptamat.2010.03.049Scripta Materialia 63, 7 (2010)2010-03-22Scripta Materialia2010-03-22637S1359-6462(10)X0014-8Viewpoint set no. 47686691http://www.scriptamat.org/article/PIIS1359646210002095/abstract?rss=yesAbstract: Grain-scale creep straining processes in die-cast and permanent-mold-cast Mg–Al–Ca alloys have been studied. High-temperature strain mapping with electron backscattered diffraction analysis reveals favorably oriented grains deforming preferentially during creep. Displacements of microstructural-scale markers applied along grain boundaries and within grain interiors demonstrate no significant contribution of grain boundary sliding to creep. Creep rates at 175°C display an inverse dependence on grain size, with fine-grained die-cast material possessing the highest creep resistance. Implications for the design of future alloys are discussed.Grain-scale creep processes in Mg–Al–Ca base alloys: Implications for alloy designN.D. Saddock, A. Suzuki, J.W. Jones, T.M. Pollock10.1016/j.scriptamat.2010.03.055Scripta Materialia 63, 7 (2010)2010-03-29Scripta Materialia2010-03-29637S1359-6462(10)X0014-8Viewpoint set no. 47692697http://www.scriptamat.org/article/PIIS1359646210000710/abstract?rss=yesAbstract: Die-cast Mg–La, Mg–Ce and Mg–Nd binary alloys varying in composition have been used to investigate creep resistance and its relation to microstructure. The remarkable differences in creep resistance observed in these alloys are shown to be related to different levels of rare earth (RE) solute supersaturated in the α-Mg matrix. The results seem to suggest that strengthening of the α-Mg matrix by solid solution and/or precipitation is more important than grain boundary reinforcement by intermetallic phases for the creep resistance of Mg–RE alloys.The relationship between microstructure and creep resistance in die-cast magnesium–rare earth alloysS.M. Zhu, M.A. Gibson, M.A. Easton, J.F. Nie10.1016/j.scriptamat.2010.02.005Scripta Materialia 63, 7 (2010)2010-02-08Scripta Materialia2010-02-08637S1359-6462(10)X0014-8Viewpoint set no. 47698703http://www.scriptamat.org/article/PIIS1359646209007982/abstract?rss=yesAbstract: The high-temperature deformation data obtained for a number of different Mg alloys by torsion and tension creep are discussed. ZM21 alloy exhibited peak flow stresses comparable to that observed in AZ31, and the equivalent strain to fracture in torsion for the two alloys was similar. In the cases of ZEK200 and ZM21, creep was found to obey the same constitutive equations as hot working, suggesting a continuity of mechanical parameters and substructure in the two regimes.High-temperature deformation and creep in Mg wrought alloysStefano Spigarelli, Mohamad El Mehtedi10.1016/j.scriptamat.2009.12.034Scripta Materialia 63, 7 (2010)2009-12-23Scripta Materialia2009-12-23637S1359-6462(10)X0014-8Viewpoint set no. 47704709http://www.scriptamat.org/article/PIIS1359646210000497/abstract?rss=yesThe potential to develop high-strength low-cost wrought Mg alloys through precipitation hardening is discussed with specific references to our recent studies on microalloyed Mg–Zn and Mg–Sn based extruded alloys.Towards the development of heat-treatable high-strength wrought Mg alloysK. Hono, C.L. Mendis, T.T. Sasaki, K. Oh-ishi10.1016/j.scriptamat.2010.01.038Scripta Materialia 63, 7 (2010)2010-01-25Scripta Materialia2010-01-25637S1359-6462(10)X0014-8Viewpoint set no. 47710715http://www.scriptamat.org/article/PIIS1359646209007635/abstract?rss=yesMicrostructure and texture evolution of Mg–6Zn–1Mn–1Al (ZMA611) and Mg–6Zn–1Y (ZW61) alloys have been investigated. It is shown that recrystallization occurs through a shear (deformation) band nucleation mechanism. Alloy composition has a significant effect on the nature of the deformation bands formed during rolling, resulting in a difference in the orientation of recrystallized grains between the two alloys: double twin-related in ZMA611 and tension twin-related in ZW61. Such a contrast in microstructure results in the two alloys having different (00.2) pole figures.Microstructure and texture evolution of Mg alloys during twin-roll casting and subsequent hot rollingKyung-Hun Kim, Byeong-Chan Suh, Jun Ho Bae, Myeong-Shik Shim, S. Kim, Nack J. Kim10.1016/j.scriptamat.2009.12.010Scripta Materialia 63, 7 (2010)2009-12-10Scripta Materialia2009-12-10637S1359-6462(10)X0014-8Viewpoint set no. 47716720http://www.scriptamat.org/article/PIIS1359646210000199/abstract?rss=yesAbstract: Extrusion textures in magnesium alloys are of high interest due to their influence on yield asymmetry. The present work describes three mechanisms of texture selection that may play a role during extrusion. These mechanisms involve localized differences in deformation at the grain level, the change in local environment experienced by grain boundary bulges and shear banding. The work employs visco-plastic crystal plasticity and electron backscattering diffraction.Texture selection mechanisms in uniaxially extruded magnesium alloysM.R. Barnett, A. Sullivan, N. Stanford, N. Ross, A. Beer10.1016/j.scriptamat.2010.01.018Scripta Materialia 63, 7 (2010)2010-01-18Scripta Materialia2010-01-18637S1359-6462(10)X0014-8Viewpoint set no. 47721724http://www.scriptamat.org/article/PIIS1359646209007970/abstract?rss=yesAbstract: Rare earth elements or yttrium can weaken the strong basal textures of magnesium sheets and are of interest for the improvement of sheet formability. The weakening of magnesium sheet textures with increasing content of Ce, Nd and Y is connected to the solid solubility of the respective element. A relationship is drawn between the weak textures and the appearance of deformation bands with compression and double twins during rolling and a grain growth restriction during annealing of the sheets.Effect of rare earth additions on microstructure and texture development of magnesium alloy sheetsK. Hantzsche, J. Bohlen, J. Wendt, K.U. Kainer, S.B. Yi, D. Letzig10.1016/j.scriptamat.2009.12.033Scripta Materialia 63, 7 (2010)2009-12-23Scripta Materialia2009-12-23637S1359-6462(10)X0014-8Viewpoint set no. 47725730http://www.scriptamat.org/article/PIIS1359646210002083/abstract?rss=yesAbstract: The tensile and compressive yielding of cast Mg–Zn alloys, with varying grain sizes and compositions ranging from 0 to 2.3at.% Zn, are simulated using a polycrystal plasticity model. The results are used to determine the grain size and composition dependences of the critical resolved shear stresses (CRSS) of basal slip and tensile twinning.Using polycrystal plasticity modeling to determine the effects of grain size and solid solution additions on individual deformation mechanisms in cast Mg alloysBabak Raeisinia, Sean R. Agnew10.1016/j.scriptamat.2010.03.054Scripta Materialia 63, 7 (2010)2010-03-29Scripta Materialia2010-03-29637S1359-6462(10)X0014-8Viewpoint set no. 47731736http://www.scriptamat.org/article/PIIS1359646210003726/abstract?rss=yesCritical resolved shear stresses (CRSSs) for slip on different types of slip systems in single-crystal hexagonal close-packed metals show very wide variations. Values derived from measurements and modelling on polycrystals show much less variability and there is often evidence for activation of “hard” slip modes from dislocation observations in transmission electron microscopy. We show that this discrepancy originates in the hardening processes that take place in polycrystals, which must be treated as a term that is additive to the true CRSS.Effective values of critical resolved shear stress for slip in polycrystalline magnesium and other hcp metalsW.B. Hutchinson, M.R. Barnett10.1016/j.scriptamat.2010.05.047Scripta Materialia 63, 7 (2010)2010-06-07Scripta Materialia2010-06-07637S1359-6462(10)X0014-8Viewpoint set no. 47737740http://www.scriptamat.org/article/PIIS1359646210000588/abstract?rss=yesAbstract: We discuss the nucleation of deformation twins in Mg from a fundamental perspective. Atomistic simulations reveal twinning mechanisms and suggest that twin nucleation most likely occurs at grain boundaries (GBs). We observe twin nucleation from symmetrical tilt grain boundaries using molecular dynamics and reveal that the nucleation pathway depends on the tilt angle and the GB defect state. In particular, twin nucleation is preferred at GBs with low misorientation angles, in agreement with electron back-scattering diffraction (EBSD) analyses. A probabilistic description of twin nucleation is then proposed with the aim of linking atomic-scale information with meso-scale EBSD statistical analyses.An atomic and probabilistic perspective on twin nucleation in MgJ. Wang, I.J. Beyerlein, C.N. Tomé10.1016/j.scriptamat.2010.01.047Scripta Materialia 63, 7 (2010)2010-02-01Scripta Materialia2010-02-01637S1359-6462(10)X0014-8Viewpoint set no. 47741746http://www.scriptamat.org/article/PIIS1359646210001594/abstract?rss=yesAbstract: Fatigue tests were performed on AZ31 Mg alloys at room temperature in tension cycles. Deformation twinning of the type was observed both below and above the fatigue limit, indicating that the twins do not contribute directly to fatigue failure. However, prismatic slip and substantial cyclic hardening were observed above the fatigue limit. Progressive hardening gave rise to double twinning that led to the formation of large surface steps, cracks and eventual failure.Roles of deformation twinning and dislocation slip in the fatigue failure mechanism of AZ31 Mg alloysJ. Koike, N. Fujiyama, D. Ando, Y. Sutou10.1016/j.scriptamat.2010.03.021Scripta Materialia 63, 7 (2010)2010-03-08Scripta Materialia2010-03-08637S1359-6462(10)X0014-8Viewpoint set no. 47747750http://www.scriptamat.org/article/PIIS1359646210003738/abstract?rss=yesAbstract: The fatigue properties of an extruded Mg–3Al–0Mn magnesium alloy component were evaluated experimentally. Fully reversed, strain control fatigue tests were conducted on specimens extracted from regions with a varying grain size and texture. Scanning electron microscopy was employed to establish structure–property relations between microstructure and cyclic damage. Relations were drawn between microstructural features such as particle size, grain size, initial Taylor factor and the number of cycles to failure.Structure–property relations of cyclic damage in a wrought magnesium alloyJ.D. Bernard, J.B. Jordon, M.F. Horstemeyer, H. El Kadiri, J. Baird, David Lamb, Alan A. Luo10.1016/j.scriptamat.2010.05.048Scripta Materialia 63, 7 (2010)2010-06-10Scripta Materialia2010-06-10637S1359-6462(10)X0014-8Viewpoint set no. 47751756http://www.scriptamat.org/article/PIIS1359646210003465/abstract?rss=yesHighly photoactive, nanocrystalline WO3 films were fabricated by an economic solution process based on polymer-assisted direct deposition. The optimized film exhibited a photocurrent of 2.3mAcm−2 (at 1.23V vs. reversible hydrogen electrode) under simulated solar illumination (air mass 1.5 global) and a maximum incident photon to current efficiency of 71% at an incident wavelength of 340nm. The observed performance represents one of the highest values reported for WO3. High crystallinity, porosity and optimum thickness of nanocrystalline films were identified as the critical variables that induce the high photoactivity.Nanocrystalline WO3 film with high photo-electrochemical activity prepared by polymer-assisted direct depositionSuk Joon Hong, Hwichan Jun, Jae Sung Lee10.1016/j.scriptamat.2010.05.021Scripta Materialia 63, 7 (2010)2010-05-24Scripta Materialia2010-05-24637S1359-6462(10)X0014-8Regular articles757760http://www.scriptamat.org/article/PIIS1359646210003568/abstract?rss=yesThe lattice parameter of expanded austenite was determined as a function of the content of interstitially dissolved carbon in homogeneous, carburized thin stainless steel foils. For the first time this expansion of the face-centered cubic lattice is determined on unstrained austenite. It is found that a linear relation holds between the lattice parameter, a, and the occupancy of the octahedral interstices, yC. The results are compared to other values in the literature and discussed in terms of stressed and unstressed austenite.Lattice expansion of carbon-stabilized expanded austeniteThomas S. Hummelshøj, Thomas L. Christiansen, Marcel A.J. Somers10.1016/j.scriptamat.2010.05.031Scripta Materialia 63, 7 (2010)2010-05-31Scripta Materialia2010-05-31637S1359-6462(10)X0014-8Regular articles761763http://www.scriptamat.org/article/PIIS1359646210003921/abstract?rss=yesThe crystallization behavior of Ti-based metallic glassy powders was systematically investigated. The results show a novel metastable nanocrystallization process, i.e. the glassy powders exhibit multi-step phase transition behavior. For the first exothermic event, the entire glassy phase crystallized into metastable nanocrystals, then a face-centered cubic structured Ni2SnZr and a monoclinic structured TiNi0.8Cu0.2 phases formed by a solid state transition (the second exothermic event). These crystallizations are believed to be driven by the synergetic effect of thermodynamics and kinetics.Metastable nanocrystallization behavior of Ti-based metallic glassy powders during post-heatingD.J. Wang, Y.J. Huang, J. Zou, G.J. Auchterlonie, K.S. Jack, J. Shen10.1016/j.scriptamat.2010.06.007Scripta Materialia 63, 7 (2010)2010-06-07Scripta Materialia2010-06-07637S1359-6462(10)X0014-8Regular articles764767http://www.scriptamat.org/article/PIIS1359646210003957/abstract?rss=yesThe influences of the amorphous matrix and crystalline dendrite phases on the hardness and elastic moduli of Zr/Ti-based bulk metallic glass matrix composites have been assessed. While the moduli of the composites correspond to those predicted by the rule of mixtures, the hardness of the composites is similar to that of the matrix, suggesting that the plastic flow in the composites under constrained conditions such as indentation is controlled by the flow resistance of the contiguous matrix.On the hardness and elastic modulus of bulk metallic glass matrix compositesR.L. Narayan, K. Boopathy, Indrani Sen, D.C. Hofmann, U. Ramamurty10.1016/j.scriptamat.2010.06.010Scripta Materialia 63, 7 (2010)2010-06-10Scripta Materialia2010-06-10637S1359-6462(10)X0014-8Regular articles768771http://www.scriptamat.org/article/PIIS1359646210003969/abstract?rss=yesA method for fabricating high-strain-rate superplastic Mg alloys in sheet form by using a high-ratio differential speed rolling process is described. The ingot-metallurgy processed Mg alloy exhibited a superplastic performance comparable to that of powder-metallurgy counterparts. By optimizing the controlling parameters in the rolling process, an ultrafine-grained microstructure with good thermal stability, which is the desired microstructure for achieving high-strain-rate superplasticity, could be obtained using only a few processing steps.Synthesis of high-strain-rate superplastic magnesium alloy sheets using a high-ratio differential speed rolling techniqueW.J. Kim, B.H. Lee, J.B. Lee, M.J. Lee, Y.B. Park10.1016/j.scriptamat.2010.06.011Scripta Materialia 63, 7 (2010)2010-06-10Scripta Materialia2010-06-10637S1359-6462(10)X0014-8Regular articles772775http://www.scriptamat.org/article/PIIS1359646210004008/abstract?rss=yesStable ferromagnetism in nitrogen-doped cubic ZrO2 is reported based on first-principles calculations. A substitution of oxygen by nitrogen introduces spin-polarized 2p states near the Fermi level, producing a total magnetic moment of 1.0 μB. The hole-mediated direct 2p–2p interaction and indirect 2p–4p/4d–2p interaction result in a long-range ferromagnetic ground state. With large magnetization energy, room temperature ferromagnetism is expected. Additionally, the Zr-rich condition with NO as N source is suggested to realize the N doping in cubic ZrO2.Ferromagnetism in nitrogen-doped cubic ZrO2: Density-functional investigationsWei Zhou, Pengfei Xing, Lijuan Liu, Ping Wu10.1016/j.scriptamat.2010.06.015Scripta Materialia 63, 7 (2010)2010-06-11Scripta Materialia2010-06-11637S1359-6462(10)X0014-8Regular articles776779http://www.scriptamat.org/article/PIIS1359646210003982/abstract?rss=yesBiFeO3 (BFO) and La-doped BFO (BLFO) thin films were grown on Pt/TiO2/SiO2/Si substrate using pulsed laser deposition. The domain structures of the BFO and BLFO were investigated via piezoresponse force microscopy. Highly enhanced ferroelectric properties with great remanent polarization (Pr) of 102μCcm−2 and decreased leakage current density were obtained via La doping. The magnetic property was also increased by the La doping, ascribed to spatial homogenization of the spin arrangement. The mechanisms for the enhancement of ferroelectric and ferromagnetic characteristics are discussed.Enhanced multiferroic properties and domain structure of La-doped BiFeO3 thin filmsF. Yan, T.J. Zhu, M.O. Lai, L. Lu10.1016/j.scriptamat.2010.06.013Scripta Materialia 63, 7 (2010)2010-06-11Scripta Materialia2010-06-11637S1359-6462(10)X0014-8Regular articles780783http://www.scriptamat.org/article/PIIS1359646210003994/abstract?rss=yesZinc antimonides exhibit high thermoelectric figures of merit and bear great potential for power generation. To advance the understanding of the structure–property relationship in these alloys, the microstructure of a nanocrystalline Zn4Sb3 alloy, containing 57.29at.% Zn, was investigated by scanning electron microscopy and atom probe tomography. Chemical inhomogeneities were observed at grain boundaries. Within the grains the distribution of Zn shows large fluctuations inducing a complex microstructure made of Zn-rich and Sb-rich regions at a nanometer scale.High-resolution nanostructural investigation of Zn4Sb3 alloysBaptiste Gault, Emmanuelle A. Marquis, David W. Saxey, Gareth M. Hughes, Dominique Mangelinck, Eric S. Toberer, G. Jeff Snyder10.1016/j.scriptamat.2010.06.014Scripta Materialia 63, 7 (2010)2010-06-11Scripta Materialia2010-06-11637S1359-6462(10)X0014-8Regular articles784787http://www.scriptamat.org/article/PIIS1359646210004033/abstract?rss=yesA numerical modeling, which is hierarchically coupled with the crystal plasticity finite element method and discrete dislocation dynamics, was performed to examine thermal fatigue behavior of via pattern in ultra-large-scale copper interconnections. The pattern had a pillar shape and one of three crystallographic orientations, 〈001〉, 〈110〉 and 〈111〉, along its longitudinal direction. The internal stress and surface morphology on via patterns could be obtained considering the generation of dislocations and their motion. A robust via pattern in terms of crystallographic orientation was suggested.A discrete dislocation dynamics modeling for thermal fatigue of preferred oriented copper via patternsGyu Seok Kim, Marc C. Fivel, Hyo-Jong Lee, Chansun Shin, Heung Nam Han, Hyung-Jun Chang, Kyu Hwan Oh10.1016/j.scriptamat.2010.06.018Scripta Materialia 63, 7 (2010)2010-06-16Scripta Materialia2010-06-16637S1359-6462(10)X0014-8Regular articles788791