Acta Materialia最新文献_第9页

Buckling of thin films: Lateral growth and kinetic evolution of telephone cords 薄膜的弯曲电话线的横向生长和动力学演变

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-24 DOI: 10.1016/j.actamat.2024.120505

Senjiang Yu , Ibrahim Goda , Guillaume Parry , Julien Durinck , Yong Ni , Christophe Coupeau

{"title":"Buckling of thin films: Lateral growth and kinetic evolution of telephone cords","authors":"Senjiang Yu , Ibrahim Goda , Guillaume Parry , Julien Durinck , Yong Ni , Christophe Coupeau","doi":"10.1016/j.actamat.2024.120505","DOIUrl":"10.1016/j.actamat.2024.120505","url":null,"abstract":"<div><div>We conduct a thorough investigation of the lateral growth and kinetic evolution of telephone cord buckles within thin films, employing both experimental and numerical techniques. Our exploration begins with <em>in-situ</em> experiments conducted on annealed silicon nitride films, aimed at capturing empirical data on the formation and evolution of these distinctive patterns. These experiments yield valuable insights into the morphological changes of telephone cords, such as wave flipping and merging, which lead to the enlargement of buckles at double wavelengths and widths. Subsequently, we employ a combined approach of geometrically nonlinear plate modeling and surface-based cohesive interface framework within a finite element numerical model to analyze the interplay between buckling-induced delamination and growth triggered by mode mixity-dependent interfacial toughness. Through this integrated approach, we effectively capture the mutual evolution of buckling and delamination occurrences, thus highlighting their inherently dynamic nature. Our numerical simulations show that the width and wavelength of telephone cords are doubled, consistent with experimental findings.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120505"},"PeriodicalIF":8.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488651","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}

引用次数: 0

Investigating the thermal decomposition of BP into B12P2: experimental insights and kinetic modelling at high temperatures 研究 BP 热分解为 B12P2：高温下的实验启示和动力学建模

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-24 DOI: 10.1016/j.actamat.2024.120495

Yves Tahan , Olivier Rapaud , Nicolas Pradeilles , Pierre Carles , Alexandre Maître , Sarah Dine , Dominique Vrel , Hicham Moutaabbid , Yann Le Godec , Cécile Genevois , Mathieu Allix

{"title":"Investigating the thermal decomposition of BP into B12P2: experimental insights and kinetic modelling at high temperatures","authors":"Yves Tahan , Olivier Rapaud , Nicolas Pradeilles , Pierre Carles , Alexandre Maître , Sarah Dine , Dominique Vrel , Hicham Moutaabbid , Yann Le Godec , Cécile Genevois , Mathieu Allix","doi":"10.1016/j.actamat.2024.120495","DOIUrl":"10.1016/j.actamat.2024.120495","url":null,"abstract":"<div><div>This study investigates the thermal decomposition of BP into B<sub>12</sub>P<sub>2</sub>, with a particular focus on the heterogeneous solid-gas mechanism involving BP powders synthesized via self-propagating high temperature reactions. Various techniques, including XRD, TGA, SEM, TEM, EELS and SAED, were combined to examine morphological and structural changes at different temperatures. The results reveal an ignition temperature for decomposition at 1120 °C, beyond which BP grains undergo fragmentation into smaller particles, accompanied by the release of phosphorous gases (P<sub>2(g)</sub>, P<sub>4(g)</sub>). Additionally, Rietveld refinements on thermally treated powders facilitated the determination of advancement rate values of the decomposition reaction under different isothermal conditions. Based on these kinetic data obtained at 1300 °C, a one-process nucleation-growth model with instantaneous nucleation and anisotropic growth has be established. In particular, the law, which describes the process for a spherical grain with inward development and a reaction occurring at the internal interface as the step determining the rate, displayed a strong correlation coefficient, offering novel insights into the kinetic evolution of the BP to B<sub>12</sub>P<sub>2</sub> conversion. These results contribute to a deeper understanding of the thermal decomposition process and its underlying elementary mechanisms.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120495"},"PeriodicalIF":8.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488097","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}

引用次数: 0

Anisotropy of plastic flow in Zr-2.5Nb pressure tube material analysed using a viscoplastic self-consistent approach 利用粘弹性自稳方法分析 Zr-2.5Nb 压力管材料中塑料流动的抗变形性

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-24 DOI: 10.1016/j.actamat.2024.120503

N. Christodoulou , C.N. Tomé

{"title":"Anisotropy of plastic flow in Zr-2.5Nb pressure tube material analysed using a viscoplastic self-consistent approach","authors":"N. Christodoulou , C.N. Tomé","doi":"10.1016/j.actamat.2024.120503","DOIUrl":"10.1016/j.actamat.2024.120503","url":null,"abstract":"<div><div>Plastic anisotropy is observed during plastic flow in samples from the axial and transverse directions of Zr-2.5Nb pressure tubes used in CANDU<span><span><sup>1</sup></span></span> nuclear reactors tested in uniaxial tension. Plastic anisotropy was also measured in shear by testing in torsion ‘mini’ pressure tubes from the same material. Room temperature results from these experiments were analysed using a visco-plastic self-consistent model that takes into account the crystallographic texture of the material and allows for the single crystal work hardening behaviour to be described by means of a deformation law specific to each slip system.</div><div>The visco-plastic self-consistent model was used to derive: <strong>(i)</strong> the evolution with strain of the critical resolved shear stress values consistent with prismatic, basal and pyramidal dislocation glide, <strong>(ii)</strong> the evolution of slip system activity as a function of strain, and <strong>(iii)</strong> the values of Hill's plastic anisotropy coefficients that are consistent with the observed anisotropy of yielding and their dependence on accumulated strain. The model also allows for the prediction of the components of the flow stress tensor that cannot be measured experimentally and their dependence on the work hardening behaviour of pressure tube material. Moreover, the yield surface after different amounts of plastic strain was calculated using the visco-plastic self-consistent model, compared to the one that results from using the Hill's anisotropy coefficients. Our work exposes the limitations of the Hill ellipsoid for describing plastic yield when microstructural evolution is present.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120503"},"PeriodicalIF":8.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488096","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}

引用次数: 0

Modeling of the perovskite nickelate SmNiO3 nucleation from amorphous thin films: A Volmer's thermodynamical approach 非晶态薄膜中的包晶镍酸盐 SmNiO3 成核模型：沃尔默热力学方法

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-24 DOI: 10.1016/j.actamat.2024.120509

Silvère Barrat, Zil Fernández-Gutiérrez, Carlos Calvo-Mola, Pierre-Antoine Tostivint, Stéphanie Bruyère, David Pilloud, Fabien Capon

{"title":"Modeling of the perovskite nickelate SmNiO3 nucleation from amorphous thin films: A Volmer's thermodynamical approach","authors":"Silvère Barrat, Zil Fernández-Gutiérrez, Carlos Calvo-Mola, Pierre-Antoine Tostivint, Stéphanie Bruyère, David Pilloud, Fabien Capon","doi":"10.1016/j.actamat.2024.120509","DOIUrl":"10.1016/j.actamat.2024.120509","url":null,"abstract":"<div><div>We present a thermodynamical model based on Volmer's nucleation theory adapted to the case of the perovskite nickelate SmNiO<sub>3</sub> crystallization (SNO) from an amorphous (aSNO) thin film. This amorphous phase is synthesized via reactive magnetron sputtering and then subsequently annealed in air at temperatures between 725 and 925 K to crystallize it. This model allows to predict the theoretical nucleation rate of the crystallized perovskite phase according to the annealing temperature, the type of the nucleation (homogeneous and heterogeneous mechanisms) and to estimate some physical and thermodynamical data related to this transformation. A theoretical evaluation of the nucleation rate shows that the optimum temperature for crystallization is close to 800 K for which the nucleation rate can reach 10<sup>21</sup> m<sup>-3</sup>.s<sup>-1</sup> if considering both homogeneous and heterogeneous nucleation mechanisms. As the annealing temperature moves away from 800 K, the theoretical nucleation rate drops drastically, as observed experimentally by X-ray Diffraction (XRD) when we annealed 200 nm thick aSNO films. The good agreement between the presented model and the experimental crystallization results allows us to numerically evaluate some physical parameters not yet reported to date in the literature for SNO perovskites such as the surface energy between the amorphous and the crystallized SNO phases, the strain energy when the crystallization occurs and the enthalpy associated with crystallization.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120509"},"PeriodicalIF":8.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489187","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}

引用次数: 0

MXene quantum dots-Co(OH)2 heterojunction stimulated Co2+δ sites for boosted alkaline hydrogen evolution MXene 量子点-Co(OH)2 异质结激发 Co2+δ 位点促进碱性氢气演化

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-23 DOI: 10.1016/j.actamat.2024.120507

Yuhua Liu , Wei Zhang , Xu Zou , Yan Yan , Qing Liang , Fuxi Liu , Wenwen Li , Kexin Song , Xinyan Zhou , Zhongjun Chen , Weitao Zheng

{"title":"MXene quantum dots-Co(OH)2 heterojunction stimulated Co2+δ sites for boosted alkaline hydrogen evolution","authors":"Yuhua Liu , Wei Zhang , Xu Zou , Yan Yan , Qing Liang , Fuxi Liu , Wenwen Li , Kexin Song , Xinyan Zhou , Zhongjun Chen , Weitao Zheng","doi":"10.1016/j.actamat.2024.120507","DOIUrl":"10.1016/j.actamat.2024.120507","url":null,"abstract":"<div><div>Persevering structural stability of the active species after phase reconfiguration poses a key challenge for various sustainable catalytic systems. In this study, we construct a robust β-Co(OH)<sub>2</sub> electrocatalyst via self-adaptive coordination of MXene quantum dots (MQDs) during phase transition from the Co<sub>2</sub>(OH)<sub>3</sub>Cl precursor to β-Co(OH)<sub>2</sub> (MQDs/β-Co(OH)<sub>2</sub>/Co foam). The heterojunction induced the excellent electron transfer, causing the lattice strain of β-Co(OH)<sub>2</sub>, and the accumulated electrons at the MQDs end regulated the electronic density of Co sites (Co<sup>2+δ</sup>), reversing the structural instability of β-Co(OH)<sub>2</sub> within the applied reduction potential range. Furthermore, density functional theory calculation confirms the role of well-matched heterogeneous interfaces in HER. The result shows the high-valance Co<sup>2+δ</sup> sites promote adsorption and dissociation of H<sub>2</sub>O, increasing proton supply and accelerating reaction rate. Concurrently, MQDs facilitate the adsorption of hydrogen intermediates and H<sub>2</sub> generation. Our architected catalyst exhibited exceptional alkaline hydrogen evolution reactions (HERs) performance (91 mV@10 mA cm<sup>−2</sup>) and superior stability outperforms most reported β-Co(OH) <sub>2</sub>-based catalysts. Our work demonstrates the efficacy of MQDs as co-catalysts in enhancing the activity and structural stability of catalysts.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120507"},"PeriodicalIF":8.3,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488098","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}

引用次数: 0

Defect engineering of charge transport and photovoltaic effect in BiFeO3 films BiFeO3 薄膜中电荷传输和光伏效应的缺陷工程学

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-22 DOI: 10.1016/j.actamat.2024.120481

Alfredo Blázquez Martínez , Barnik Mandal , Sebastjan Glinsek , Torsten Granzow

{"title":"Defect engineering of charge transport and photovoltaic effect in BiFeO3 films","authors":"Alfredo Blázquez Martínez , Barnik Mandal , Sebastjan Glinsek , Torsten Granzow","doi":"10.1016/j.actamat.2024.120481","DOIUrl":"10.1016/j.actamat.2024.120481","url":null,"abstract":"<div><div>Bismuth ferrite (BiFeO<sub>3</sub>) is an attractive multiferroic material, extensively explored in photoferroelectric investigations. However, its applications are hindered by the high leakage current, requiring precise control of charge transport properties. Defect engineering has emerged as a promising strategy to address this issue: controlling the defect chemistry, particularly oxygen vacancies, is key to tuning the electrical properties. This study investigates the influence of 5% <figure><img></figure> - and 2% <figure><img></figure> -doping on the dark and light-induced charge transport properties of polycrystalline BiFeO<sub>3</sub> films. Our results demonstrate that <figure><img></figure> reduces dark conductivity by decreasing oxygen vacancy concentration with no change in the physical nature of the charge transport mechanism. In contrast, <figure><img></figure> modifies the charge transport mechanism, increasing low-field (E <span><math><mo><</mo></math></span> 100kVcm<sup>-1</sup>) dark conductivity while drastically reducing high-field (E <span><math><mo>></mo></math></span> 250kVcm<sup>-1</sup>) dark conductivity. This tuning of the defect chemistry is also key to enhance the photovoltages of the bulk photovoltaic effect in BiFeO<sub>3</sub>. High photoinduced electric fields up to 7kVcm<sup>-1</sup> and low photoconductivity values are obtained with <figure><img></figure> -doping, while high short-circuit photocurrent values are obtained with <figure><img></figure> -doping.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"283 ","pages":"Article 120481"},"PeriodicalIF":8.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142452658","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}

引用次数: 0

Excellent radiation resistance via enforced local non-directional He diffusion in a WTaCrV multicomponent alloy containing coherent ordered nanoprecipitates 在含有相干有序纳米沉淀物的 WTaCrV 多组分合金中，通过强化局部非定向 He 扩散实现优异的抗辐射性能

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-22 DOI: 10.1016/j.actamat.2024.120501

Xinkai Wang , Qiankun Yang , Weisong Wu , Wei Zhang , Yong Zhang , Dingshun Yan , Kefu Gan , Bin Liu , Zhiming Li

{"title":"Excellent radiation resistance via enforced local non-directional He diffusion in a WTaCrV multicomponent alloy containing coherent ordered nanoprecipitates","authors":"Xinkai Wang , Qiankun Yang , Weisong Wu , Wei Zhang , Yong Zhang , Dingshun Yan , Kefu Gan , Bin Liu , Zhiming Li","doi":"10.1016/j.actamat.2024.120501","DOIUrl":"10.1016/j.actamat.2024.120501","url":null,"abstract":"<div><div>We design and investigate a W<sub>15</sub>Ta<sub>15</sub>Cr<sub>35</sub>V<sub>35</sub> (at.%) multicomponent alloy (MCA) with exceptional radiation resistance. The sintered WTaCrV alloy exhibits a body-centered cubic (BCC) matrix with dispersed coherent ordered nanoprecipitates. After ∼3-hour irradiation under 400 keV He<sup>+</sup> at room temperature (RT) and 450 °C with a fluence of 2 × 10<sup>17</sup> ions/cm<sup>2</sup>, the irradiation hardening values of the MCA are about a quarter of those of pure tungsten counterparts irradiated at identical conditions. Besides, helium bubbles generated in the irradiated matrix of the MCA are much smaller, compared with those in the pure tungsten and other tungsten-rich alloys previously reported. The exceptional radiation resistance of the present WTaCrV alloy can be mainly attributed to two synergistic mechanisms. First, the high lattice distortion of the solid solution matrix promotes the local non-directional diffusion of irradiation defects, effectively suppressing the aggregation of irradiation defects and helium atoms along specific orientations. This facilitates more uniform nucleation of helium bubbles in the alloy matrix. Second, carbon was introduced during fast hot pressing sintering as interstitial solute to form carbon-rich coherent ordered nanoprecipitates. The carbon-vacancy complexes generated in the nanoprecipitates inhibit the nucleation and aggregation of helium atoms at the vacancies during He<sup>+</sup> irradiation. The above two mechanisms synergistically enhance the resistance against He<sup>+</sup> irradiation. This work thus demonstrates a design strategy for high radiation resistance alloys by introducing well-tuned ordered coherent nanoprecipitates in multicomponent alloy systems.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120501"},"PeriodicalIF":8.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142486904","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}

引用次数: 0

Thermodynamics and kinetics of long-range ordering in FCC Ni–33at.%Cr alloys: Insights from atomic scale modeling 催化裂化镍-33%铬合金长程有序化的热力学和动力学：原子尺度建模的启示

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-22 DOI: 10.1016/j.actamat.2024.120486

Liangzhao Huang , Thomas Schuler , Chu-Chun Fu , Daniel Brimbal , Frédéric Soisson

{"title":"Thermodynamics and kinetics of long-range ordering in FCC Ni–33at.%Cr alloys: Insights from atomic scale modeling","authors":"Liangzhao Huang , Thomas Schuler , Chu-Chun Fu , Daniel Brimbal , Frédéric Soisson","doi":"10.1016/j.actamat.2024.120486","DOIUrl":"10.1016/j.actamat.2024.120486","url":null,"abstract":"<div><div>This study investigates the thermodynamics and kinetics of the Ni<img>Cr system, focusing specifically on the kinetics of the order–disorder phase transformation in the Ni–33at.%Cr alloy. Combining density functional theory, CALPHAD-type models, and experimental diffusion data, we introduce and validate an efficient pair interaction model (PIM) and use it in Monte Carlo simulations. Our results include a detailed phase diagram of Ni<img>Cr in face-centered cubic structure and kinetic models that delineate the behavior of solid solutions at high temperatures and ordered structures at low temperatures. The simulations shed light on tracer diffusion and ordering kinetics within Ni–33at.%Cr, demonstrating good agreement with existing experimental data. Furthermore, our simulation-driven insights prompt a reevaluation of certain aspects of related experimental studies concerning the apparent ordering activation enthalpies and growth kinetics. We also provide a thorough discussion on the strengths of our models and features for future improvement.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120486"},"PeriodicalIF":8.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142486903","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}

引用次数: 0

The deformation mechanisms responsible for strain localization in nanotwinned nickel alloys 纳米绕纹镍合金应变局部化的变形机制

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-22 DOI: 10.1016/j.actamat.2024.120502

Mo-Rigen He, Arunima Banerjee, Kevin J. Hemker

{"title":"The deformation mechanisms responsible for strain localization in nanotwinned nickel alloys","authors":"Mo-Rigen He, Arunima Banerjee, Kevin J. Hemker","doi":"10.1016/j.actamat.2024.120502","DOIUrl":"10.1016/j.actamat.2024.120502","url":null,"abstract":"<div><div>Nanotwinned Ni-Mo-W alloys possess a combination of unique mechanical and thermal properties, such as ultrahigh strength and microstructural stability, which are correlated with the presence of densely packed growth twins. In a previous study, the ultrahigh compressive strength of Ni<sub>84</sub>Mo<sub>11</sub>W<sub>5</sub> (atomic percent) micropillars was associated with the formation of highly localized shear bands, but the trigger for such localized plasticity was not identified. Here, Ni<sub>86</sub>Mo<sub>3</sub>W<sub>11</sub> (atomic percent) micropillars were carefully compressed to various levels to uncover the nanoscale deformation mechanisms that trigger the strain localization. Post-mortem transmission electron microscopy investigations of pillars after the first measurable strain burst revealed ∼50 nm thick shear bands consisting of reoriented and twin-free grains, while the columnar grains adjacent to the shear bands were partly detwinned. More importantly, unlike the Mo-rich pillars, the W-rich pillars showed discernible plasticity before the first strain burst. Close inspection made before the formation of a mature shear band revealed a detwinning region of ∼30 nm thickness that aligned more parallel to the coherent twin boundaries, and multiple nanotwins truncated with incoherent twin boundaries were resolved between the detwinning band and the nanotwinned grains. These observations strongly suggest detwinning, facilitated by migration of incoherent twin boundaries, to be the precursor to strain localization and the intensive shear banding observed in nanotwinned Ni-Mo-W alloys. Comparing the present results with the literature further highlights the general role of detwinning in governing the plastic behavior of nanotwinned alloys with a wide range of stacking fault energy.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120502"},"PeriodicalIF":8.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142452593","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}

引用次数: 0

On microstructure development during laser melting and resolidification: An experimentally validated simulation study 激光熔化和分解过程中的微观结构发展：经实验验证的模拟研究

IF 8.3 1区材料科学

Acta Materialia Pub Date : 2024-10-22 DOI: 10.1016/j.actamat.2024.120482

Alexander F. Chadwick , Juan Guillermo Santos Macías , Arash Samaei , Gregory J. Wagner , Manas V. Upadhyay , Peter W. Voorhees

{"title":"On microstructure development during laser melting and resolidification: An experimentally validated simulation study","authors":"Alexander F. Chadwick , Juan Guillermo Santos Macías , Arash Samaei , Gregory J. Wagner , Manas V. Upadhyay , Peter W. Voorhees","doi":"10.1016/j.actamat.2024.120482","DOIUrl":"10.1016/j.actamat.2024.120482","url":null,"abstract":"<div><div>Integrating experiment and simulation provides invaluable insights into the critical parameters that determine the microstructure of alloys produced by additive manufacturing. Here, the grain structure formation due to solidification during single pass laser scans (mimicking bead-on-plate single tracks) on a 316L stainless steel is studied <em>in situ</em> inside a scanning electron microscope that is directly integrated with a continuous-wave laser. The grain size distribution before melting is used as an initial condition in a coupled phase-field/thermal multiphysics modeling framework. The predicted resolidified microstructures are found to agree favorably with those observed experimentally for multiple laser powers and scan velocities, indicating the validity of the overall model. Grain morphology is analyzed quantitatively, and the top surfaces are compared between the experiments and simulations. Analysis of the three-dimensional grain shapes predicted by the simulations shows that the length of the major axis of the resolidified grains is sensitive to laser power and scan speeds, while the length of the minor axis is not. Furthermore, the preferential alignment of the major axes of the grains depends on the melt pool geometry.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"282 ","pages":"Article 120482"},"PeriodicalIF":8.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142486905","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}

引用次数: 0