Pub Date : 2026-02-01Epub Date: 2025-12-18DOI: 10.1016/j.ijplas.2025.104583
Xinxin Sun , Lu Wang , Guochen Peng , Gengwen Wang , Yisheng Lu , Shinji Sakane , Wentao Yan , M.W. Fu
<div><div>Despite decades of development in high-energy-density (HED) beam additive manufacturing (AM), modeling and simulation of thermomechanical behavior and microstructure evolution have predominantly been performed in pseudo-coupled or one-way coupled modes. This restriction limits its application in multi-track prediction and impedes a comprehensive understanding of the underlying mechanisms in HED beam AM processes. Therefore, this work presents the first two-way, fully coupled, multi-phase field crystal plasticity finite element method (MPF-CPFEM) model, which simultaneously simulates microstructure evolution and thermomechanical behavior during AM processes. The unified MPF model captures recrystallization, grain growth, and liquid–solid transformation, while the CPFEM accounts for polycrystalline deformation, dislocation density evolution, and temperature-dependent thermomechanical response. A mesh-sharing scheme and real-time data exchange enable two-way coupling, supported by a developed element-free Galerkin finite difference method (EFG-FDM) for the accurate calculation of non-local data on deformed meshes, including geometrically necessary dislocations (GNDs) and phase fields. The model incorporates the influence of cellular structure size effects via GND densities derived from the supercooling rate. The validated model is applied to two laser powder bed fusion (LPBF) cases. It replicates morphological characteristics, such as V-shaped grains and the non-uniform surface of the molten pool. Simulations reveal strong two-way coupling between thermomechanical response and heterogeneous deformation. It shows that epitaxially grown regions exhibit different stress and grain orientations from the substrate due to the influence of cellular structures, thermomechanical deformation, and intergranular constraints driven by the molten pool with grain aggregates. The model reveals residual stress accumulation during the dual-track LPBF case and identifies potential crack regions at epitaxial grain boundaries. It captures ultra-rapid dislocation multiplication after limited tracks, which differs from the conventional plastic forming process, cyclic service environment, and solid-state AM processes. Rapid cooling suppresses discontinuous dynamic recrystallization (DDRX), while continuous dynamic recrystallization (CDRX) is found to form after limited laser tracks, driven by extreme deformation at molten pool boundaries in the LPBF process. The application to the dual-track LPBF case demonstrates its inherent capability to tackle the challenge of fully coupling multi-track AM simulations, which is challenging with conventional one-way modeling. As the first endeavor in a fully coupled modeling framework for AM processes, the MPF-CPFEM model offers unique insights into the complex HED beam AM mechanisms. Limitations and prospects, including computational efficiency, potential extension to additional AM processes, computational optimizations, and f
{"title":"A fully coupled multi-physics multi-phase field crystal plasticity finite element model (MPF-CPFEM) for predicting microstructure evolution and thermomechanical behavior in additive manufacturing","authors":"Xinxin Sun , Lu Wang , Guochen Peng , Gengwen Wang , Yisheng Lu , Shinji Sakane , Wentao Yan , M.W. Fu","doi":"10.1016/j.ijplas.2025.104583","DOIUrl":"10.1016/j.ijplas.2025.104583","url":null,"abstract":"<div><div>Despite decades of development in high-energy-density (HED) beam additive manufacturing (AM), modeling and simulation of thermomechanical behavior and microstructure evolution have predominantly been performed in pseudo-coupled or one-way coupled modes. This restriction limits its application in multi-track prediction and impedes a comprehensive understanding of the underlying mechanisms in HED beam AM processes. Therefore, this work presents the first two-way, fully coupled, multi-phase field crystal plasticity finite element method (MPF-CPFEM) model, which simultaneously simulates microstructure evolution and thermomechanical behavior during AM processes. The unified MPF model captures recrystallization, grain growth, and liquid–solid transformation, while the CPFEM accounts for polycrystalline deformation, dislocation density evolution, and temperature-dependent thermomechanical response. A mesh-sharing scheme and real-time data exchange enable two-way coupling, supported by a developed element-free Galerkin finite difference method (EFG-FDM) for the accurate calculation of non-local data on deformed meshes, including geometrically necessary dislocations (GNDs) and phase fields. The model incorporates the influence of cellular structure size effects via GND densities derived from the supercooling rate. The validated model is applied to two laser powder bed fusion (LPBF) cases. It replicates morphological characteristics, such as V-shaped grains and the non-uniform surface of the molten pool. Simulations reveal strong two-way coupling between thermomechanical response and heterogeneous deformation. It shows that epitaxially grown regions exhibit different stress and grain orientations from the substrate due to the influence of cellular structures, thermomechanical deformation, and intergranular constraints driven by the molten pool with grain aggregates. The model reveals residual stress accumulation during the dual-track LPBF case and identifies potential crack regions at epitaxial grain boundaries. It captures ultra-rapid dislocation multiplication after limited tracks, which differs from the conventional plastic forming process, cyclic service environment, and solid-state AM processes. Rapid cooling suppresses discontinuous dynamic recrystallization (DDRX), while continuous dynamic recrystallization (CDRX) is found to form after limited laser tracks, driven by extreme deformation at molten pool boundaries in the LPBF process. The application to the dual-track LPBF case demonstrates its inherent capability to tackle the challenge of fully coupling multi-track AM simulations, which is challenging with conventional one-way modeling. As the first endeavor in a fully coupled modeling framework for AM processes, the MPF-CPFEM model offers unique insights into the complex HED beam AM mechanisms. Limitations and prospects, including computational efficiency, potential extension to additional AM processes, computational optimizations, and f","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104583"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784643","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}
Pub Date : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.ijplas.2025.104584
Yuquan Meng , Xia Zeng , Shanshan Liu , Wanghui Li , Yunjiang Wang , Kaikai Song , Jianli Shao , Lijun Xiao , Weidong Song
Phase transformation offers a promising strategy to overcome the long-standing strength-toughness trade-off in materials by accommodating plastic deformation through strain redistribution. The FCC high entropy alloy (HEA) CoCuFeNiPd has received attention for its excellent mechanical properties due to its intense chemical short-range order (SRO)and severe lattice distortion effect (LD). In this study, the effect of SRO and LD, as well as strain rate, on the mechanical responses and phase transformation behavior of CoCuFeNiPd HEA is investigated via a combination of molecular dynamics (MD) and Monte Carlo (MC) simulations. This study demonstrates that the deformation mechanism in CoCuFeNiPd HEA transitions from dislocation slip dominance at 1 × 10⁸/s to FCC-BCCHCP phase transformation dominance at 1 × 10¹⁰/s. During the initial deformation stage, yield behavior is controlled by BCC structure nucleation. LD effects substantially reduce the nucleation barrier, promoting premature BCC formation and accelerating the yielding process. The SRO effect induces the phase transformations that predominantly occur in regions where Cu-Fe-Pd clusters aggregate, which promotes the rapid development of dislocations and maintains a high flow stress. In addition, the twinning substructures of BCC martensite by specific atom shear movements are observed under the strain rate of 1010/s, which maintains the high strength, and the subsequent HCP phase transformation provides the continuous plastic deformation. This study provides important insights into the stress-induced phase transformation mechanism under extreme strain rates.
{"title":"Effect of lattice distortion and chemical short-range order on the phase transformation behavior of high entropy alloys under high strain rates","authors":"Yuquan Meng , Xia Zeng , Shanshan Liu , Wanghui Li , Yunjiang Wang , Kaikai Song , Jianli Shao , Lijun Xiao , Weidong Song","doi":"10.1016/j.ijplas.2025.104584","DOIUrl":"10.1016/j.ijplas.2025.104584","url":null,"abstract":"<div><div>Phase transformation offers a promising strategy to overcome the long-standing strength-toughness trade-off in materials by accommodating plastic deformation through strain redistribution. The FCC high entropy alloy (HEA) CoCuFeNiPd has received attention for its excellent mechanical properties due to its intense chemical short-range order (SRO)and severe lattice distortion effect (LD). In this study, the effect of SRO and LD, as well as strain rate, on the mechanical responses and phase transformation behavior of CoCuFeNiPd HEA is investigated via a combination of molecular dynamics (MD) and Monte Carlo (MC) simulations. This study demonstrates that the deformation mechanism in CoCuFeNiPd HEA transitions from dislocation slip dominance at 1 × 10⁸/s to FCC-BCC<img>HCP phase transformation dominance at 1 × 10¹⁰/s. During the initial deformation stage, yield behavior is controlled by BCC structure nucleation. LD effects substantially reduce the nucleation barrier, promoting premature BCC formation and accelerating the yielding process. The SRO effect induces the phase transformations that predominantly occur in regions where Cu-Fe-Pd clusters aggregate, which promotes the rapid development of dislocations and maintains a high flow stress. In addition, the twinning substructures of BCC martensite by specific atom shear movements are observed under the strain rate of 10<sup>10</sup>/s, which maintains the high strength, and the subsequent HCP phase transformation provides the continuous plastic deformation. This study provides important insights into the stress-induced phase transformation mechanism under extreme strain rates.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104584"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784644","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}
Pub Date : 2026-02-01Epub Date: 2025-12-29DOI: 10.1016/j.ijplas.2025.104593
Jin Wang , Nicolas J. Peter , Martin Heilmaier , Ruth Schwaiger
Refractory compositionally complex alloys (RCCAs) are known for their exceptional high-temperature resistance. However, their inherent brittleness at room temperature limits broader practical applications. To explore the effects of microstructure and loading conditions on their deformation behavior, micromechanical experiments, including microbending and micropillar compression tests, were performed on two representative RCCAs: equimolar NbMoCrTiAl (ordered B2 crystal structure) and TaNbHfZrTi (disordered A2 crystal structure). Both alloys demonstrated significant plastic deformation, with strains exceeding 40% at room temperature. Despite prior reports of limited ductility in NbMoCrTiAl at the millimeter scale, our micropillar compression tests on single-crystalline pillars oriented along and reveal substantial plasticity. The dominant deformation mechanisms in NbMoCrTiAl were identified as crystallographic slip and cross-slip of screw dislocations. By contrast, TaNbHfZrTi exhibited a broader range of mechanisms, including screw dislocation slip and a high density of non-screw dislocations, accompanied by kink band formation and activation of high-order slip planes, which collectively contribute to its remarkable ductility among the highest reported for body-centered cubic RCCAs. The atomic size mismatch inherent in compositionally complex alloys enhances dislocation mobility, while the random distribution of elements promotes the formation of edge segments, further improving ductility. These findings highlight the critical role of microstructural characteristics in tailoring the deformation behavior of RCCAs for room-temperature applications.
{"title":"A micromechanical investigation of plasticity in ordered NbMoCrTiAl and disordered TaNbHfZrTi refractory compositionally complex alloys at room temperature","authors":"Jin Wang , Nicolas J. Peter , Martin Heilmaier , Ruth Schwaiger","doi":"10.1016/j.ijplas.2025.104593","DOIUrl":"10.1016/j.ijplas.2025.104593","url":null,"abstract":"<div><div>Refractory compositionally complex alloys (RCCAs) are known for their exceptional high-temperature resistance. However, their inherent brittleness at room temperature limits broader practical applications. To explore the effects of microstructure and loading conditions on their deformation behavior, micromechanical experiments, including microbending and micropillar compression tests, were performed on two representative RCCAs: equimolar NbMoCrTiAl (ordered B2 crystal structure) and TaNbHfZrTi (disordered A2 crystal structure). Both alloys demonstrated significant plastic deformation, with strains exceeding 40% at room temperature. Despite prior reports of limited ductility in NbMoCrTiAl at the millimeter scale, our micropillar compression tests on single-crystalline pillars oriented along <span><math><mrow><mo>〈</mo><mn>1</mn><mspace></mspace><mn>0</mn><mspace></mspace><mn>0</mn><mo>〉</mo></mrow></math></span> and <span><math><mrow><mo>〈</mo><mn>1</mn><mspace></mspace><mn>1</mn><mspace></mspace><mn>0</mn><mo>〉</mo></mrow></math></span> reveal substantial plasticity. The dominant deformation mechanisms in NbMoCrTiAl were identified as crystallographic slip and cross-slip of screw dislocations. By contrast, TaNbHfZrTi exhibited a broader range of mechanisms, including screw dislocation slip and a high density of non-screw dislocations, accompanied by kink band formation and activation of high-order slip planes, which collectively contribute to its remarkable ductility among the highest reported for body-centered cubic RCCAs. The atomic size mismatch inherent in compositionally complex alloys enhances dislocation mobility, while the random distribution of elements promotes the formation of edge segments, further improving ductility. These findings highlight the critical role of microstructural characteristics in tailoring the deformation behavior of RCCAs for room-temperature applications.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104593"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145881652","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}
Accelerating the prediction of mechanical behaviour in heterogenous materials is critical for large-scale microstructure optimization and realizing functionally optimized materials. While existing machine learning approaches have demonstrated an ability to accelerate predictions for the full-field mechanical response of a wide range of heterogenous microstructures, they have been largely limited to monotonic loading conditions. This paper introduces U-PolyConformer, a spatiotemporal machine learning framework that combines U-Net convolutional neural networks with transformer layers, capable of capturing the full-field stress and strain evolution under monotonic and random walk loading conditions. Trained on a large dataset of crystal plasticity finite element method (CPFEM) simulations with FCC polycrystals, the model accurately captures complex phenomena, including strain localization and stress unloading. The U-PolyConformer achieves a 7,900x speed-up over the ground-truth CPFEM simulations while producing high-fidelity results in both interpolative and extrapolative regimes. Comprehensive evaluations demonstrate the U-PolyConformer’s capacity to generalize outside the training distribution to novel microstructures, loading conditions, and strain hardening behaviours. To highlight the model’s potential as a surrogate for accelerating computational materials engineering workflows, a microstructure optimization framework based on static recrystallization is introduced and used to delay the onset of localization. This framework is successfully used to identify the grains which initiate the onset of localization, illustrating how the proposed model and optimization framework may be used for identifying and exploring property-performance relationships.
{"title":"U-PolyConformer: Spatiotemporal machine learning for microstructure engineering","authors":"Dylan Budnick , Benhour Amirian , Abhijit Brahme , Haitham El-Kadiri , Kaan Inal","doi":"10.1016/j.ijplas.2025.104597","DOIUrl":"10.1016/j.ijplas.2025.104597","url":null,"abstract":"<div><div>Accelerating the prediction of mechanical behaviour in heterogenous materials is critical for large-scale microstructure optimization and realizing functionally optimized materials. While existing machine learning approaches have demonstrated an ability to accelerate predictions for the full-field mechanical response of a wide range of heterogenous microstructures, they have been largely limited to monotonic loading conditions. This paper introduces U-PolyConformer, a spatiotemporal machine learning framework that combines U-Net convolutional neural networks with transformer layers, capable of capturing the full-field stress and strain evolution under monotonic and random walk loading conditions. Trained on a large dataset of crystal plasticity finite element method (CPFEM) simulations with FCC polycrystals, the model accurately captures complex phenomena, including strain localization and stress unloading. The U-PolyConformer achieves a 7,900x speed-up over the ground-truth CPFEM simulations while producing high-fidelity results in both interpolative and extrapolative regimes. Comprehensive evaluations demonstrate the U-PolyConformer’s capacity to generalize outside the training distribution to novel microstructures, loading conditions, and strain hardening behaviours. To highlight the model’s potential as a surrogate for accelerating computational materials engineering workflows, a microstructure optimization framework based on static recrystallization is introduced and used to delay the onset of localization. This framework is successfully used to identify the grains which initiate the onset of localization, illustrating how the proposed model and optimization framework may be used for identifying and exploring property-performance relationships.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104597"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822859","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}
Pub Date : 2026-02-01Epub Date: 2025-12-23DOI: 10.1016/j.ijplas.2025.104594
Shabnam Konica, Brian W. Sheldon, Vikas Srivastava
We present a continuum-level electro-chemo-mechanical framework that captures the coupled influence of stress and electrochemistry on the morphological evolution of viscoplastic Li-metal anodes and solid electrolyte interphase (SEI) layers in liquid-electrolyte Li-metal batteries. Our model incorporates a two-way coupling between mechanical deformation and electrochemical transport, including stress-modulated Li-ion migration across the SEI, large deformation viscoplasticity of the Li-anode during plating/stripping cycles, and surface energy effects at the anode interface. This multiphysics approach enables a systematic investigation of how electrochemical (e.g., diffusivity, conductivity), mechanical (e.g., modulus, residual stress), and geometric (e.g., thickness) properties of the SEI affect interfacial stability. Through numerical simulations, we generate design maps that quantify the roles of SEI geometry, material properties, and current density in either suppressing or amplifying surface instabilities. Crucially, our results highlight the dominant role of Li-metal viscoplasticity in driving surface roughening – even under homogeneous SEI conditions – a factor often overlooked in earlier linear stability or decoupled studies. We also explore the performance of composite and bi-layer SEIs, offering insights into optimal combinations of mechanical stiffness and interfacial energy to block protrusion growth. Together, this work offers a predictive modeling tool and design guidance for engineering artificial SEIs to suppress dendrite formation and enable fast, stable cycling of Li-metal batteries.
{"title":"A continuum study of the role of coupled electrochemistry and stress on the morphological evolution of Li-anode","authors":"Shabnam Konica, Brian W. Sheldon, Vikas Srivastava","doi":"10.1016/j.ijplas.2025.104594","DOIUrl":"10.1016/j.ijplas.2025.104594","url":null,"abstract":"<div><div>We present a continuum-level electro-chemo-mechanical framework that captures the coupled influence of stress and electrochemistry on the morphological evolution of viscoplastic Li-metal anodes and solid electrolyte interphase (SEI) layers in liquid-electrolyte Li-metal batteries. Our model incorporates a two-way coupling between mechanical deformation and electrochemical transport, including stress-modulated Li-ion migration across the SEI, large deformation viscoplasticity of the Li-anode during plating/stripping cycles, and surface energy effects at the anode interface. This multiphysics approach enables a systematic investigation of how electrochemical (e.g., diffusivity, conductivity), mechanical (e.g., modulus, residual stress), and geometric (e.g., thickness) properties of the SEI affect interfacial stability. Through numerical simulations, we generate design maps that quantify the roles of SEI geometry, material properties, and current density in either suppressing or amplifying surface instabilities. Crucially, our results highlight the dominant role of Li-metal viscoplasticity in driving surface roughening – even under homogeneous SEI conditions – a factor often overlooked in earlier linear stability or decoupled studies. We also explore the performance of composite and bi-layer SEIs, offering insights into optimal combinations of mechanical stiffness and interfacial energy to block protrusion growth. Together, this work offers a predictive modeling tool and design guidance for engineering artificial SEIs to suppress dendrite formation and enable fast, stable cycling of Li-metal batteries.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104594"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823727","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}
Pub Date : 2026-02-01Epub Date: 2025-11-25DOI: 10.1016/j.ijplas.2025.104568
Peng Jing , Bin Shao , Yingying Zong , Hongxi Liu
The excellent strength and toughness of nanotwinned Al, which can be further improved, make it suitable for interconnects in flexible electronic components. The key is to fully understand the precise physical nature of detwinning at extremely small twin boundary spacings. In this study, molecular dynamics simulations were conducted to investigate the anisotropic detwinning behaviors in nanotwinned Al. When there is no resolved shear stress on the twin boundaries, simulation results indicate that detwinning does not occur upon yield, but only after twin rotation. Twin rotation and the local interaction between dislocations drive detwinning. Directional dislocation propagation induces twin rotation, ultimately resulting in the formation of subgrains and shear bands. The overall intensity of detwinning decreases with increasing twin boundary spacing. When the loading direction is oriented at a 45° angle to the twin boundaries, almost exclusively detwinning dislocations are activated throughout the entire deformation process, a behavior that is independent of twin boundary spacing. The grains within nanotwinned polycrystals exhibit anisotropic detwinning behaviors. The influence of detwinning on mechanical properties is not apparent until a substantial degree of detwinning has accumulated. Detwinning is enhanced at higher temperatures but suppressed under higher strain rates. The kinetic analysis of the detwinning process demonstrates that the mechanisms identified in this study are applicable to experimental conditions. A model was proposed to describe the relationship between the twin rotation angle and twin boundary spacing. These findings further deepen the understanding of the anisotropic detwinning mechanisms in nanotwinned metals.
{"title":"Anisotropic detwinning behaviors in nanotwinned aluminum: An atomistic simulation study","authors":"Peng Jing , Bin Shao , Yingying Zong , Hongxi Liu","doi":"10.1016/j.ijplas.2025.104568","DOIUrl":"10.1016/j.ijplas.2025.104568","url":null,"abstract":"<div><div>The excellent strength and toughness of nanotwinned Al, which can be further improved, make it suitable for interconnects in flexible electronic components. The key is to fully understand the precise physical nature of detwinning at extremely small twin boundary spacings. In this study, molecular dynamics simulations were conducted to investigate the anisotropic detwinning behaviors in nanotwinned Al. When there is no resolved shear stress on the twin boundaries, simulation results indicate that detwinning does not occur upon yield, but only after twin rotation. Twin rotation and the local interaction between dislocations drive detwinning. Directional dislocation propagation induces twin rotation, ultimately resulting in the formation of subgrains and shear bands. The overall intensity of detwinning decreases with increasing twin boundary spacing. When the loading direction is oriented at a 45° angle to the twin boundaries, almost exclusively detwinning dislocations are activated throughout the entire deformation process, a behavior that is independent of twin boundary spacing. The grains within nanotwinned polycrystals exhibit anisotropic detwinning behaviors. The influence of detwinning on mechanical properties is not apparent until a substantial degree of detwinning has accumulated. Detwinning is enhanced at higher temperatures but suppressed under higher strain rates. The kinetic analysis of the detwinning process demonstrates that the mechanisms identified in this study are applicable to experimental conditions. A model was proposed to describe the relationship between the twin rotation angle and twin boundary spacing. These findings further deepen the understanding of the anisotropic detwinning mechanisms in nanotwinned metals.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104568"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145594126","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}
Pub Date : 2026-02-01Epub Date: 2025-12-22DOI: 10.1016/j.ijplas.2025.104599
Mingjie Zhang , Hui Guo , Jianke Qiu , Xiaobing Hu , Chao Fang , Hao Wang , Dongsheng Xu , Yingjie Ma , Jiafeng Lei , Rui Yang
In this work, the strain rate effects on the Ti-6Al-4V ELI alloy under uniaxial tensile loading were systematically investigated over a wide range of strain rates, from quasi-static to dynamic conditions with nominal strain rates ranging from 0.001 to 1000 s-1. Electron backscatter diffraction technique was used to characterize the evolutions of the mean geometrically necessary dislocation (GND) density and twin boundary fraction with increasing strain rate, while transmission electron microscopy was used to examine changes in dislocation structures. The results reveal the presence of a critical strain rate near 50 s-1, which divides the strain rate strengthening behavior into two distinct regimes, each characterized by markedly different strain rate sensitivity (SRS) exponents (). The contrasting trends in value, GND density and twin content indicate a strain rate-induced transition in dominant deformation mechanism—from slip-dominated behavior at lower strain rates to slip-twinning dominated behavior at higher strain rates, which arises from the competitive interplay between dislocation slip and deformation twinning. Additionally, the SRSs of various slip systems and the twinning mode were evaluated through a combination of experimental characterizations and molecular dynamics simulations. Among these, prismatic ⟨a⟩ slip exhibits the highest SRS, explaining its reduced activity under dynamic loading conditions, while twinning, with relatively low SRS, exhibits elevated activity.
{"title":"Strain rate-driven transition between dislocation slip and twinning in Ti-6Al-4V ELI alloy during tensile deformation","authors":"Mingjie Zhang , Hui Guo , Jianke Qiu , Xiaobing Hu , Chao Fang , Hao Wang , Dongsheng Xu , Yingjie Ma , Jiafeng Lei , Rui Yang","doi":"10.1016/j.ijplas.2025.104599","DOIUrl":"10.1016/j.ijplas.2025.104599","url":null,"abstract":"<div><div>In this work, the strain rate effects on the Ti-6Al-4V ELI alloy under uniaxial tensile loading were systematically investigated over a wide range of strain rates, from quasi-static to dynamic conditions with nominal strain rates ranging from 0.001 to 1000 s<sup>-1</sup>. Electron backscatter diffraction technique was used to characterize the evolutions of the mean geometrically necessary dislocation (GND) density and twin boundary fraction with increasing strain rate, while transmission electron microscopy was used to examine changes in dislocation structures. The results reveal the presence of a critical strain rate near 50 s<sup>-1</sup>, which divides the strain rate strengthening behavior into two distinct regimes, each characterized by markedly different strain rate sensitivity (SRS) exponents (<span><math><mi>m</mi></math></span>). The contrasting trends in <span><math><mi>m</mi></math></span> value, GND density and twin content indicate a strain rate-induced transition in dominant deformation mechanism—from slip-dominated behavior at lower strain rates to slip-twinning dominated behavior at higher strain rates, which arises from the competitive interplay between dislocation slip and deformation twinning. Additionally, the SRSs of various slip systems and the <span><math><mrow><mrow><mo>{</mo><mrow><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>2</mn></mrow><mo>}</mo></mrow><mrow><mo>〈</mo><mrow><mover><mn>1</mn><mo>¯</mo></mover><mn>011</mn></mrow><mo>〉</mo></mrow></mrow></math></span> twinning mode were evaluated through a combination of experimental characterizations and molecular dynamics simulations. Among these, prismatic ⟨<em>a</em>⟩ slip exhibits the highest SRS, explaining its reduced activity under dynamic loading conditions, while twinning, with relatively low SRS, exhibits elevated activity.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104599"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813011","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}
Pub Date : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.ijplas.2025.104585
Linxiang Liu , Qingfeng Wu , Zhijun Wang , Hyoung Seop Kim , Junjie Li , Lei Wang , Feng He , Jincheng Wang
L12-strengthened FCC/B2 dual-phase high-entropy alloys (HEAs) exhibit excellent mechanical performance across a broad temperature range, positioning them promising candidates for high-temperature structural applications. However, microstructural coarsening and associated mechanical degradation under prolonged thermal exposure remain key challenges. In this study, a representative alloy with the composition Ni41.9Co19Cr10Fe10Al15Mo2Ti2B0.1 (at. %) was subjected to long-term aging at 800 °C, revealing an unusual microstructural evolution. Beyond the expected L12 coarsening within the FCC phase, an interfacial L12 shell formed via the progressive consumption of L12 precipitates from both the FCC and B2 phases, ultimately encapsulating the B2 domains. This transformation produced a unique three-level hierarchical architecture: FCC matrix with intragranular L12 precipitates, an interfacial L12 shell, and a B2 core. Remarkably, despite this pronounced microstructural evolution, the alloy maintained stable strength-ductility synergy from room temperature up to 800 °C. This stability is attributed to the additional strengthening imparted by the interfacial L12 shell and the favorable cooperative deformation among the FCC, B2, and interfacial L12 phases. A quantitative strengthening model was established, revealing that the strengthening contribution of the L12 shell increases with increasing shell thickness and exceeds 100 MPa after 720 h of aging. These results provide valuable guidance for the design of thermally stable precipitation-strengthened dual-phase HEAs for long-term high-temperature applications.
{"title":"Hierarchical interfacial L12 shell formation enables stable high-temperature mechanical performance in FCC/B2 dual-phase high-entropy alloys","authors":"Linxiang Liu , Qingfeng Wu , Zhijun Wang , Hyoung Seop Kim , Junjie Li , Lei Wang , Feng He , Jincheng Wang","doi":"10.1016/j.ijplas.2025.104585","DOIUrl":"10.1016/j.ijplas.2025.104585","url":null,"abstract":"<div><div>L1<sub>2</sub>-strengthened FCC/B2 dual-phase high-entropy alloys (HEAs) exhibit excellent mechanical performance across a broad temperature range, positioning them promising candidates for high-temperature structural applications. However, microstructural coarsening and associated mechanical degradation under prolonged thermal exposure remain key challenges. In this study, a representative alloy with the composition Ni<sub>41.9</sub>Co<sub>19</sub>Cr<sub>10</sub>Fe<sub>10</sub>Al<sub>15</sub>Mo<sub>2</sub>Ti<sub>2</sub>B<sub>0.1</sub> (at. %) was subjected to long-term aging at 800 °C, revealing an unusual microstructural evolution. Beyond the expected L1<sub>2</sub> coarsening within the FCC phase, an interfacial L1<sub>2</sub> shell formed via the progressive consumption of L1<sub>2</sub> precipitates from both the FCC and B2 phases, ultimately encapsulating the B2 domains. This transformation produced a unique three-level hierarchical architecture: FCC matrix with intragranular L1<sub>2</sub> precipitates, an interfacial L1<sub>2</sub> shell, and a B2 core. Remarkably, despite this pronounced microstructural evolution, the alloy maintained stable strength-ductility synergy from room temperature up to 800 °C. This stability is attributed to the additional strengthening imparted by the interfacial L1<sub>2</sub> shell and the favorable cooperative deformation among the FCC, B2, and interfacial L1<sub>2</sub> phases. A quantitative strengthening model was established, revealing that the strengthening contribution of the L1<sub>2</sub> shell increases with increasing shell thickness and exceeds 100 MPa after 720 h of aging. These results provide valuable guidance for the design of thermally stable precipitation-strengthened dual-phase HEAs for long-term high-temperature applications.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104585"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145777635","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}
Pub Date : 2026-02-01Epub Date: 2025-12-25DOI: 10.1016/j.ijplas.2025.104600
Ruo-Fei Yuan , Yong Zhang , Yu Zhang , Bo Dong , Yong-Ji Wang , Zhe Zhang , Tang Gu , Yun-Fei Jia , Fu-Zhen Xuan
Harmonic-structured (HS) metallic materials have garnered significant interest owing to their exceptional strength–ductility synergy, yet grain-scale fracture mechanisms remain poorly elucidated, impeding the formulation of predictive strategies for strength–toughness balancing. To address this gap, we fabricated HS CoCrFeMnNi high-entropy alloys with tailored fine-grain (FG) shell fractions. Quasi-in situ tensile experiments monitored via electron backscatter diffraction (EBSD) and crystal plasticity finite element/cohesive zone modeling (CPFEM–CZM) reveal that FG regions exhibit high crack susceptibility due to pronounced strain gradients—particularly at coarse-grain (CG)/FG interfaces and within fine-grained zones—that evolve with strain and intensify stress concentration through deformation incompatibility, thereby promoting preferential crack nucleation and propagation. Conversely, CG regions enable sustained plastic energy dissipation via superior intrinsic deformability. Cracks nucleate and propagate preferentially within FG zones, while CG domains dissipate energy via plasticity and microcracking, diverting energy from primary crack growth. As cracks propagate into CG regions, they activate multiple slip systems, generating strain gradients that increase geometrically necessary dislocation density near crack tips. This elevates back stress, inducing crack blunting and enhancing fracture tolerance. Crucially, an optimal FG fraction (31.4%) prevents premature crack nucleation in FG regions while maintaining strength unattainable in low-FG HS variants, thereby preserving material continuity. This dual-phase synergy ensures superior fracture resistance and strength-toughness balance in HS alloys. Our work elucidates intrinsic fracture resistance mechanisms of HS microstructures and quantifies the effects of FG fraction on damage tolerance, establishing essential microstructural design criteria for advanced metallic materials.
{"title":"Revealing fracture-resistant design principles in harmonic-structured high-entropy alloys using quasi in situ experiments and integrated modeling","authors":"Ruo-Fei Yuan , Yong Zhang , Yu Zhang , Bo Dong , Yong-Ji Wang , Zhe Zhang , Tang Gu , Yun-Fei Jia , Fu-Zhen Xuan","doi":"10.1016/j.ijplas.2025.104600","DOIUrl":"10.1016/j.ijplas.2025.104600","url":null,"abstract":"<div><div>Harmonic-structured (HS) metallic materials have garnered significant interest owing to their exceptional strength–ductility synergy, yet grain-scale fracture mechanisms remain poorly elucidated, impeding the formulation of predictive strategies for strength–toughness balancing. To address this gap, we fabricated HS CoCrFeMnNi high-entropy alloys with tailored fine-grain (FG) shell fractions. Quasi-in situ tensile experiments monitored via electron backscatter diffraction (EBSD) and crystal plasticity finite element/cohesive zone modeling (CPFEM–CZM) reveal that FG regions exhibit high crack susceptibility due to pronounced strain gradients—particularly at coarse-grain (CG)/FG interfaces and within fine-grained zones—that evolve with strain and intensify stress concentration through deformation incompatibility, thereby promoting preferential crack nucleation and propagation. Conversely, CG regions enable sustained plastic energy dissipation via superior intrinsic deformability. Cracks nucleate and propagate preferentially within FG zones, while CG domains dissipate energy via plasticity and microcracking, diverting energy from primary crack growth. As cracks propagate into CG regions, they activate multiple slip systems, generating strain gradients that increase geometrically necessary dislocation density near crack tips. This elevates back stress, inducing crack blunting and enhancing fracture tolerance. Crucially, an optimal FG fraction (31.4%) prevents premature crack nucleation in FG regions while maintaining strength unattainable in low-FG HS variants, thereby preserving material continuity. This dual-phase synergy ensures superior fracture resistance and strength-toughness balance in HS alloys. Our work elucidates intrinsic fracture resistance mechanisms of HS microstructures and quantifies the effects of FG fraction on damage tolerance, establishing essential microstructural design criteria for advanced metallic materials.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104600"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145844921","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}
Single-phase CoCrNi-based multi-principal element alloys (MPEAs) are recognized for their excellent fatigue damage tolerance. To further enhance their performance, a small amount of Mo was introduced into the CoCrNi system, resulting in the Co35.4Cr22.9Ni35.5Mo6.2 (commercially known as MP35N). This study investigates its tensile and low-cycle fatigue behavior at room temperature. The alloy, with an average grain size of ∼67 µm, exhibits a yield strength of 303 ± 8 MPa, an ultimate tensile strength of 800 ± 7 MPa, and a total-elongation-to-failure of 75 ± 3%. Its pronounced work-hardening and high ductility arise from its low stacking fault energy (SFE), which enables the concurrent activation of planar slip and deformation twinning. Under cyclic loading, the alloy shows pronounced initial cyclic hardening, followed by strain amplitude-dependent responses. Away from fatigue cracks, deformation is governed by planar slip of extended dislocations, whose multiplication and interactions generate sessile stacking-fault nodes and Lomer–Cottrell locks, driving cyclic hardening. At low strain amplitudes (±0.3% and ±0.5%), dislocations remain homogeneously distributed within the grains, with no twinning away from the fatigue cracks. In contrast, at higher strain amplitude (±0.7%), dislocation density increases, accompanied by a growing tendency to rearrange into low-energy structures and localized deformation twinning, as the cyclic peak stresses exceed the critical twinning stress. Surface relief-assisted fatigue cracks predominantly initiate parallel to coherent annealing twin boundaries (ATBs), with fewer occurrences across ATBs, or along/across grain boundaries. This behaviour is governed by slip compatibility and transfer metrics, evaluated through the Taylor factor, elastic stiffness contrast, ATB–loading-axis orientation, Schmid factor, and the Luster–Morris parameter. Near fatigue cracks, high local stresses activate deformation twinning at all strain amplitudes, which is intersected and sheared by shear bands. Twinning contributes to strengthening, while shear bands nucleate within pre-twinned regions, leading to twin bending, necking, detwinning, and the formation of nano-subgrains, which facilitate localized softening. Compared to other CoCrNi-based MPEAs, this Mo-alloyed variant achieves higher peak stresses and comparable or improved fatigue life. These enhancements stem from Mo-induced strengthening and the alloy’s low SFE, which promotes reversible planar slip, suppresses dislocation rearrangement into low-energy structures such as walls, veins, and cells, and amplifies twinning and shear banding near cracks. Collectively, these mechanisms define the overall cyclic stress response, accommodate localised plastic strain, generate tortuous crack paths, and slow crack growth, thereby conferring fatigue resistance that approaches that of dual-phase MPEAs.
{"title":"Superior fatigue response of CoCrNi-based multi-principal element alloy with Mo addition","authors":"Shubham Sisodia , Akshat Godha , Chethan Konkati , Nikhil Suman , Govind Bajargan , Surendra Kumar Makenini , Ankur Chauhan","doi":"10.1016/j.ijplas.2025.104604","DOIUrl":"10.1016/j.ijplas.2025.104604","url":null,"abstract":"<div><div>Single-phase CoCrNi-based multi-principal element alloys (MPEAs) are recognized for their excellent fatigue damage tolerance. To further enhance their performance, a small amount of Mo was introduced into the CoCrNi system, resulting in the Co<sub>35.4</sub>Cr<sub>22.9</sub>Ni<sub>35.5</sub>Mo<sub>6.2</sub> (commercially known as MP35N). This study investigates its tensile and low-cycle fatigue behavior at room temperature. The alloy, with an average grain size of ∼67 µm, exhibits a yield strength of 303 ± 8 MPa, an ultimate tensile strength of 800 ± 7 MPa, and a total-elongation-to-failure of 75 ± 3%. Its pronounced work-hardening and high ductility arise from its low stacking fault energy (SFE), which enables the concurrent activation of planar slip and deformation twinning. Under cyclic loading, the alloy shows pronounced initial cyclic hardening, followed by strain amplitude-dependent responses. Away from fatigue cracks, deformation is governed by planar slip of extended dislocations, whose multiplication and interactions generate sessile stacking-fault nodes and Lomer–Cottrell locks, driving cyclic hardening. At low strain amplitudes (±0.3% and ±0.5%), dislocations remain homogeneously distributed within the grains, with no twinning away from the fatigue cracks. In contrast, at higher strain amplitude (±0.7%), dislocation density increases, accompanied by a growing tendency to rearrange into low-energy structures and localized deformation twinning, as the cyclic peak stresses exceed the critical twinning stress. Surface relief-assisted fatigue cracks predominantly initiate parallel to coherent annealing twin boundaries (ATBs), with fewer occurrences across ATBs, or along/across grain boundaries. This behaviour is governed by slip compatibility and transfer metrics, evaluated through the Taylor factor, elastic stiffness contrast, ATB–loading-axis orientation, Schmid factor, and the Luster–Morris parameter. Near fatigue cracks, high local stresses activate deformation twinning at all strain amplitudes, which is intersected and sheared by shear bands. Twinning contributes to strengthening, while shear bands nucleate within pre-twinned regions, leading to twin bending, necking, detwinning, and the formation of nano-subgrains, which facilitate localized softening. Compared to other CoCrNi-based MPEAs, this Mo-alloyed variant achieves higher peak stresses and comparable or improved fatigue life. These enhancements stem from Mo-induced strengthening and the alloy’s low SFE, which promotes reversible planar slip, suppresses dislocation rearrangement into low-energy structures such as walls, veins, and cells, and amplifies twinning and shear banding near cracks. Collectively, these mechanisms define the overall cyclic stress response, accommodate localised plastic strain, generate tortuous crack paths, and slow crack growth, thereby conferring fatigue resistance that approaches that of dual-phase MPEAs.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"197 ","pages":"Article 104604"},"PeriodicalIF":12.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145922260","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}
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