Acta Materialia最新文献

{"title":"Corrigendum to “Structural Organization of Phase-Separated Bioactive Glasses and the Clustering of Si, P, B, Na and F Atoms Investigated by Solid-State NMR and Monte Carlo Simulations” [Acta Materialia 259 (2023) 119203]","authors":"Anuraag Gaddam, Gregory Tricot, Przemysław Gołębiewski, Hugo R. Fernandes, Ryszard Buczynski´, Jos´e M.F. Ferreira, Hellmut Eckert","doi":"10.1016/j.actamat.2025.120905","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120905","url":null,"abstract":"The authors inform that the correct acknowledgment section should be:<br/>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"73 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the plasticity of MnS at elevated temperatures and its influence on damage prevalence","authors":"Maximilian A. Wollenweber, Jonas Werner, Carl F. Kusche, Chunhua Tian, Pei-Ling Sun, Jannik Gerlach, Talal Al-Samman, Sandra Korte-Kerzel","doi":"10.1016/j.actamat.2025.120987","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120987","url":null,"abstract":"Forming-induced damage strongly influences the service life and mechanical properties of components made from 16MnCrS5 steel. This damage is initiated in the vicinity of MnS inclusions, which fracture or delaminate at their interfaces due to the mechanical contrast to the steel matrix. Forming processes are often conducted at elevated temperatures; however, the plasticity of MnS at these temperatures in correlation with crystallographic orientation have not been fully explored. In this study, we aim to uncover to the high-temperature properties of MnS using micropillar compression and TEM analysis. We then relate them to damage prevalence observed in steel at elevated temperatures with high resolution SEM imaging in combination with AI-assisted damage analysis. We demonstrate that the mechanical contrast of MnS and steel influences the damage prevalence significantly showing a minimum at 400&lt;!-- --&gt; &lt;!-- --&gt;°C. We additionally determine the CRSS for the primary &lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;{&lt;/mo&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace width=\"0.16667em\" is=\"true\" /&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace width=\"0.16667em\" is=\"true\" /&gt;&lt;mn is=\"true\"&gt;0&lt;/mn&gt;&lt;mo is=\"true\"&gt;}&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"2.779ex\" role=\"img\" style=\"vertical-align: -0.812ex;\" viewbox=\"0 -846.5 2835.8 1196.3\" width=\"6.586ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMAIN-7B\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(500,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-31\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(1167,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-31\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\"&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(1834,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-30\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(2335,0)\"&gt;&lt;use xlink:href=\"#MJMAIN-7D\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;span role=\"presentation\"&gt;&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;{&lt;/mo&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace is=\"true\" width=\"0.16667em\"&gt;&lt;/mspace&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace is=\"true\" width=\"0.16667em\"&gt;&lt;/mspace&gt;&lt;mn is=\"true\"&gt;0&lt;/mn&gt;&lt;mo is=\"true\"&gt;}&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;script type=\"math/mml\"&gt;&lt;math&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;{&lt;/mo&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace width=\"0.16667em\" is=\"true\"&gt;&lt;/mspace&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace width=\"0.16667em\" is=\"true\"&gt;&lt;/mspace&gt;&lt;mn is=\"true\"&gt;0&lt;/mn&gt;&lt;mo is=\"true\"&gt;}&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/script&gt;&lt;/span&gt;\u0000&lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mrow is=\"true\"&gt;&lt;mo is=\"true\"&gt;&amp;#x3008;&lt;/mo&gt;&lt;mn is=\"true\"&gt;1&lt;/mn&gt;&lt;mspace width=\"","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"79 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143782787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of dislocation densities on the microscale strength of single-crystal strontium titanate","authors":"Jiawen Zhang ,&nbsp;Xufei Fang ,&nbsp;Wenjun Lu","doi":"10.1016/j.actamat.2025.121004","DOIUrl":"10.1016/j.actamat.2025.121004","url":null,"abstract":"<div><div>Dislocations in ceramics at room temperature are attracting increasing research interest. Dislocations may bring a new perspective for tuning physical and mechanical properties in advanced ceramics. Here, we investigate the dislocation density dependent micromechanical properties of single-crystal SrTiO₃ by tuning the dislocation densities (from ∼10¹⁰ m^-2 up to ∼10¹⁴ m^-2). Using micropillar compression tests, we find the samples exhibit a transition from brittle fracture (if no dislocation is present in the pillars) to plastic yield (with pre-engineered dislocations in the pillars). Within the regime of plastic deformation, the yield strength and plastic flow behavior exhibit a strong dependence on the dislocation density. The yield strength first decreases and then increases with the increase of dislocation densities. Detailed examination via post-mortem transmission electron microscopy reveals a complex evolution of the dislocation structure, highlighting the critical role played by dislocations in regulating the brittle/ductile behavior in SrTiO₃ at room temperature. Our findings shed new light on dislocation-mediated mechanical properties in ceramics and may provide designing guidelines for the prospective dislocation-based devices.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 121004"},"PeriodicalIF":8.3,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superstrong direct adhesion of Au, Ag, and Cu electrodes to oxide substrates via interfacial engineering","authors":"Eunwook Jeong, Sang-Geul Lee, Seung Min Yu, Jeongeun Chae, Seung Zeon Han, Gun-Hwan Lee, Yoshifumi Ikoma, Eun-Ae Choi, Jungheum Yun","doi":"10.1016/j.actamat.2025.121008","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121008","url":null,"abstract":"Electronic and optoelectronic devices usually include metal electrodes, particularly Au, Ag, and Cu layers, owing to their excellent conductivities. Achieving robust adhesion between these coinage metal electrode layers and various oxide substrates remains a considerable challenge due to the weak O affinities of coinage metals, specifically that of Au. Direct contact between the electrodes and substrates without electronically deficient intermediates, such as Ti and Cr adhesive layers, is highly desirable for improving device performance. In this study, we numerically hypothesize and experimentally confirm that the incorporation of excess atomic O interstitials into the Au/oxide interfaces and Au surfaces substantially enhances the direct adhesion between the Au electrodes and oxide substrates, while preserving the uniqueness of the Au electrodes. Our findings highlight the role of O interstitials as chemical bridges between Au electrodes and oxide substrates in film structures. The unprecedented direct adhesion of the Au electrodes to oxide substrates was detected (exhibiting enhanced adhesion strength from 0.02 to &gt; 50 N); this adhesion strength is substantially higher than those (&lt; 20 N) afforded by conventional techniques. The proposed strategy was extended to Cu and Ag electrodes with compelling evidence using atomic N and O interstitials. The superstrong adhesion of these metal film electrodes was realized without compromising the metal electrode integrity, paving the way for advancing the integration of metal electrodes into devices.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"33 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143766599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interface-plane parameterization for macroscopic grain boundary identification","authors":"A. Morawiec","doi":"10.1016/j.actamat.2025.120966","DOIUrl":"10.1016/j.actamat.2025.120966","url":null,"abstract":"<div><div>The geometric state of a flat boundary is frequently described using the so-called macroscopic parameters. They are a principal tool for dealing with interfaces at the continuous scale. The paper describes a new method for macroscopic identification of boundaries. The proposed approach is based on Euler angles representing orientations of the crystals. Two pairs of the angles are directly related to two vectors normal to the boundary plane in the crystal reference frames, and the new boundary representation can be viewed as a triplet composed of these vectors and the angle of rotation about the axis perpendicular to the plane. The representation resembles the ‘interface-plane scheme’, but unlike the latter, it is a proper parameterization. Basic practical aspects of the parameterization (such as equivalences due to symmetries, fundamental regions, uniform distribution of boundaries) are considered. The parameterization is applied to examination of Bulatov-Reed-Kumar model of grain boundary energy and reveals its previously unknown features. The proposed boundary identification method, apart from its use in numerical calculations, appeals to physical intuition.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 120966"},"PeriodicalIF":8.3,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical mechanics, entropy and temperature analog of dislocations moving on fluctuating resistance landscapes","authors":"Shuang Lyu ,&nbsp;Yuanhang Xia ,&nbsp;Wei Li ,&nbsp;Te Zhu ,&nbsp;Yue Chen ,&nbsp;Alfonso H.W. Ngan","doi":"10.1016/j.actamat.2025.121002","DOIUrl":"10.1016/j.actamat.2025.121002","url":null,"abstract":"<div><div>High/medium-entropy alloys, also known as complex concentrated alloys (CCAs), are so called because the mixing entropy reaches a maximum when the constituent multi-elements adopt equiatomic ratios. However, the mixing entropy relates little to mechanical strength for which these alloys are most studied. By analyzing dislocations in VCoNi via electron microscopy and molecular-dynamics from a machine interatomic potential, their energies are found to obey a maximum-entropy distribution in the random alloy state, but not in the annealed state where local chemical order (LCO) exists. The maximum-entropy distribution is characterized by an athermal, mechanical analog of temperature which relates directly to the alloy strength and dominates over the real temperature over a wide range. The entropy of dislocations is a fingerprint of LCO, and statistical mechanics is an impeccable theoretical framework for understanding dislocations and strength in CCAs.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 121002"},"PeriodicalIF":8.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ruddlesden-Popper Tolerance Factor: An Indicator Predicting Stability of 2D Ruddlesden-Popper Phases","authors":"Hyo Gyeong Shin, Eun Ho Kim, Jaeseon Kim, Hyo Kim, Donghwa Lee","doi":"10.1016/j.actamat.2025.120999","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120999","url":null,"abstract":"Two-dimensional Ruddlesden-Popper (RP) phases receive the focus of extensive research because of their unique optical and electrical properties. Accurate prediction of stable RP phases can expedite finding new RP compositions with improved properties for practical applications. However, most attempts are limited to finding new RP phases by employing time-consuming computational approaches. Although descriptors such as cationic radius ratio or Goldschmidt tolerance factor can be used alternatively, they have shown limitation in predicting stable RP phases. In this study, thus we develop a novel RP tolerance factor (&lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msub is=\"true\"&gt;&lt;mi is=\"true\"&gt;t&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;R&lt;/mi&gt;&lt;mi is=\"true\"&gt;P&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"2.202ex\" role=\"img\" style=\"vertical-align: -0.582ex;\" viewbox=\"0 -697.5 1529.9 947.9\" width=\"3.553ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMATHI-74\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(361,-150)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMATHI-52\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(537,0)\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMATHI-50\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/g&gt;&lt;/svg&gt;&lt;span role=\"presentation\"&gt;&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msub is=\"true\"&gt;&lt;mi is=\"true\"&gt;t&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;R&lt;/mi&gt;&lt;mi is=\"true\"&gt;P&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;script type=\"math/mml\"&gt;&lt;math&gt;&lt;msub is=\"true\"&gt;&lt;mi is=\"true\"&gt;t&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;R&lt;/mi&gt;&lt;mi is=\"true\"&gt;P&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/script&gt;&lt;/span&gt;) derived through machine learning based process, which exhibits high accuracy in classifying RP and non-RP phases. The &lt;span&gt;&lt;span style=\"\"&gt;&lt;/span&gt;&lt;span data-mathml='&lt;math xmlns=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;msub is=\"true\"&gt;&lt;mi is=\"true\"&gt;t&lt;/mi&gt;&lt;mrow is=\"true\"&gt;&lt;mi is=\"true\"&gt;R&lt;/mi&gt;&lt;mi is=\"true\"&gt;P&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"&gt;&lt;svg aria-hidden=\"true\" focusable=\"false\" height=\"2.202ex\" role=\"img\" style=\"vertical-align: -0.582ex;\" viewbox=\"0 -697.5 1529.9 947.9\" width=\"3.553ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"&gt;&lt;g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"&gt;&lt;g is=\"true\"&gt;&lt;g is=\"true\"&gt;&lt;use xlink:href=\"#MJMATHI-74\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(361,-150)\"&gt;&lt;g is=\"true\"&gt;&lt;use transform=\"scale(0.707)\" xlink:href=\"#MJMATHI-52\"&gt;&lt;/use&gt;&lt;/g&gt;&lt;g is=\"true\" transform=\"translate(537,0)\"&gt;&lt;use t","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"58 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Damage and self-healing mechanisms of 2D SiCf/SiC composites during high-temperature low-cycle fatigue in air: A combined in-situ acoustic emission and microscopy study","authors":"Xiaochen Wu, Ruixiao Zheng, Lu Li, Chaoli Ma, Shengkai Gong","doi":"10.1016/j.actamat.2025.121000","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.121000","url":null,"abstract":"The fatigue behavior and the corresponding damage mechanism under near-service environment are critical for the engineering applications of SiC_f/SiC composites. In this work, a combined <em>in-situ</em> acoustic emission (AE) and microscopy method was applied to investigate the high-temperature fatigue damage mechanisms above the tensile proportional limit stress of SiC_f/SiC composites. The fatigue damage modes at 1350 °C in air were identified and the AE signals could be effectively divided according to five types of damage events. Combined with the microstructure analysis, the damage and failure mechanisms of composites under different maximum stress levels were elucidated, which were dominated by the competition between matrix cracking and crack self-healing. When the maximum stress was low (100 MPa), the cracks in the chemical vapor infiltration (CVI) SiC matrix could be quickly healed at 1350°C. The specimen achieved fatigue run-out (10⁵ cycles) without failure, and the retention rate of ultimate tensile strength (UTS) and failure strain were 76.8 % and 51.2 %, respectively. The decrease in UTS was attributed to interfacial sliding reduction and fiber grain coarsening. The decrease in failure strain was mainly ascribed to the irreversible damage caused by matrix cracking and interfacial sliding. When the maximum stress was high (120–140 MPa), the crack opening displacement for the CVI-SiC matrix was so large that cracks could not be healed, and the fatigue failure was controlled by fiber oxidation degradation. This work is of great significance for a deep understanding of the fatigue behavior of SiC_f/SiC composites under near-service environment.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"1 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain-gradient elasto-plastic self-consistent crystal plasticity: Applications to predicting the evolution of geometrically necessary dislocations and size sensitive mechanical response","authors":"Zhangxi Feng,&nbsp;Marko Knezevic","doi":"10.1016/j.actamat.2025.121001","DOIUrl":"10.1016/j.actamat.2025.121001","url":null,"abstract":"<div><div>A novel strain gradient (SG) formulation of the mean-field elasto-plastic self-consistent (EPSC) crystal plasticity model is developed. The SG-EPSC formulation stems from the intragranular orientation spreads calculated from the second moments of the stress fields that give rise to the fluctuations in the lattice rotation rates in the grains of a polycrystalline aggregate. A procedure for creating spatial arrangements of the orientation spreads in grains is developed to obtain a functional form of the rotation tensor fields to facilitate the calculations of spatial derivatives. The right stretch tensors for orientations belonging to the intragranular spreads are obtained to form the polar decomposition of the elastic deformation gradients. The spatial derivatives involving the “curl” operation are then used to obtain the Nye dislocation tensor from the elastic deformation gradients. The Nye tensor is used to calculate geometrically necessary dislocations (GNDs) within the overall finite deformation formulation. A hardening law based on statistically stored dislocation density and an advanced composite grain model for handling twinning available in EPSC are enhanced to include the effects of GNDs. Finally, a GND-based backstress law is implemented to influence the activation of slip systems. The potential and utility of the developed model to efficiently simulate the evolution of GNDs, microstructure, and mechanical fields in polycrystalline metals are demonstrated via a few simulation cases including compression tests of α-Ti and a set of strain-path change deformation conditions of AA6016-T4.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"291 ","pages":"Article 121001"},"PeriodicalIF":8.3,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benchmark microgravity experiments and computations for 3D dendritic-array stability in directional solidification","authors":"Mehdi Medjkoune, Trevor Lyons, Fátima L. Mota, Jiefu Tian, Kaihua Ji, Louise Littles, Alain Karma, Nathalie Bergeon","doi":"10.1016/j.actamat.2025.120954","DOIUrl":"https://doi.org/10.1016/j.actamat.2025.120954","url":null,"abstract":"In this study, we present a comprehensive quantitative analysis of stability bands for dendritic arrays during directional solidification of a transparent succinonitrile-0.46 wt% camphor alloy, spanning a broad range of pulling velocities. Taking advantage of the microgravity environment aboard the International Space Station where most convection effects are suppressed, we obtain unique measurements that quantify the stable primary spacing range of spatially extended three-dimensional dendritic array structures under purely diffusive growth conditions. Through carefully designed velocity jump experiments and detailed examination of sub-grain boundary dynamics, we characterize key instabilities, including elimination and tertiary branching, shedding new light on the mechanisms governing dynamic dendritic spacing selection in extended 3D arrays. Phase field simulations are performed to characterize the stability limits of dendritic array structures for quantitative comparison with the flight experiments. Although the simulations capture general trends, significant deviations are noted at the upper stability boundary, indicating the influence of additional, unexplored factors. These findings contribute to a deeper understanding of dendritic growth dynamics and offer valuable benchmark data that could aid in refining predictive models and improving control of dendritic microstructures in metallurgical applications.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"4 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}