Pub Date : 2025-02-19DOI: 10.1016/j.ijplas.2025.104285
David D.S. Silva, Gustavo Bertoli, Paul Mason, Nelson D. Campos Neto, Norbert Schell, Michael J. Kaufman, Amy J. Clarke, Francisco G. Coury, Claudemiro Bolfarini
Novel face-centered cubic (FCC) phase CoCrFeMnNi-based medium- and high-entropy alloys (M/HEAs) with the following nominal compositions Co15Cr15Fe50Mn10Ni10 (Co15Cr15), Co20Cr20Fe40Mn10Ni10 (Co20Cr20), and Co25Cr25Fe30Mn10Ni10 (Co25Cr25) in at.%, were designed via metastability-engineering strategy to trigger different deformation mechanisms, such as twinning-induced plasticity (TWIP) and/or transformation-induced plasticity (TRIP). Both mechanisms are governed by the stacking fault energy (SFE), which depends on composition. Fully recrystallized samples with different grain sizes ranging from 2.7 to 102.5 µm were obtained. Tensile tests were conducted at room temperature (298 K), and Hall-Petch relationships were established. The annealed and deformed samples were characterized by a combination of electron backscatter diffraction (EBSD), high-energy synchrotron X-ray diffraction (HE-SXRD), and transmission electron microscopy (TEM) to correlate deformation microstructures with phase stability. It was revealed that grain refinement was more effective in the Co25Cr25 alloy, given by the high Hall-Petch coefficients ( = 516 MPa.µm1/2 and = 198 MPa). For a grain size of 2.7 µm, the product of yield strength (∼500 MPa) and uniform elongation (∼45%) in the Co25Cr25 alloy reaches its maximum (∼23 GPa%), achieving the optimal strength-ductility synergy. Due to the decrease in the effective SFE (from 26.6 to 3.5 mJ m-2), a transition in the dominant deformation behavior occurred from TWIP (Co15Cr15) to TWIP/TRIP (Co20Cr20) and finally to TRIP (Co25Cr25). The calculations further showed that and the total dislocation density exhibit an inverse relationship with the effective SFE. Such findings highlight the potential of compositional tuning for developing high-performance M/HEAs with designed deformation mechanisms.
{"title":"Metastability-engineering strategy in CoCrFeMnNi-based medium- and high-entropy alloys: Unraveling the interplay with recrystallization, grain growth, and mechanical properties","authors":"David D.S. Silva, Gustavo Bertoli, Paul Mason, Nelson D. Campos Neto, Norbert Schell, Michael J. Kaufman, Amy J. Clarke, Francisco G. Coury, Claudemiro Bolfarini","doi":"10.1016/j.ijplas.2025.104285","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104285","url":null,"abstract":"Novel face-centered cubic (FCC) phase CoCrFeMnNi-based medium- and high-entropy alloys (M/HEAs) with the following nominal compositions Co<sub>15</sub>Cr<sub>15</sub>Fe<sub>50</sub>Mn<sub>10</sub>Ni<sub>10</sub> (Co15Cr15), Co<sub>20</sub>Cr<sub>20</sub>Fe<sub>40</sub>Mn<sub>10</sub>Ni<sub>10</sub> (Co20Cr20), and Co<sub>25</sub>Cr<sub>25</sub>Fe<sub>30</sub>Mn<sub>10</sub>Ni<sub>10</sub> (Co25Cr25) in at.%, were designed via metastability-engineering strategy to trigger different deformation mechanisms, such as twinning-induced plasticity (TWIP) and/or transformation-induced plasticity (TRIP). Both mechanisms are governed by the stacking fault energy (SFE), which depends on composition. Fully recrystallized samples with different grain sizes ranging from 2.7 to 102.5 µm were obtained. Tensile tests were conducted at room temperature (298 K), and Hall-Petch relationships were established. The annealed and deformed samples were characterized by a combination of electron backscatter diffraction (EBSD), high-energy synchrotron X-ray diffraction (HE-SXRD), and transmission electron microscopy (TEM) to correlate deformation microstructures with phase stability. It was revealed that grain refinement was more effective in the Co25Cr25 alloy, given by the high Hall-Petch coefficients (<span><math><msub is=\"true\"><mi is=\"true\">k</mi><mrow is=\"true\"><mi is=\"true\">H</mi><mi is=\"true\">P</mi></mrow></msub></math></span> = 516 MPa.µm<sup>1/2</sup> and <span><math><msub is=\"true\"><mi is=\"true\">σ</mi><mn is=\"true\">0</mn></msub></math></span> = 198 MPa). For a grain size of 2.7 µm, the product of yield strength (∼500 MPa) and uniform elongation (∼45%) in the Co25Cr25 alloy reaches its maximum (∼23 GPa%), achieving the optimal strength-ductility synergy. Due to the decrease in the effective SFE (from 26.6 to 3.5 mJ m<sup>-2</sup>), a transition in the dominant deformation behavior occurred from TWIP (Co15Cr15) to TWIP/TRIP (Co20Cr20) and finally to TRIP (Co25Cr25). The calculations further showed that <span><math><msub is=\"true\"><mi is=\"true\">k</mi><mrow is=\"true\"><mi is=\"true\">H</mi><mi is=\"true\">P</mi></mrow></msub></math></span> and the total dislocation density exhibit an inverse relationship with the effective SFE. Such findings highlight the potential of compositional tuning for developing high-performance M/HEAs with designed deformation mechanisms.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"22 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451446","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 : 2025-02-16DOI: 10.1016/j.ijplas.2025.104275
Zhen Yu, Xingyue Sun, Ruisi Xing, Xu Chen
The ratcheting behavior of plastic deformation accumulation under asymmetric loading poses significant risks to the safe service of engineering structures. For accurate prediction of the ratcheting behavior of the material, a physics-informed multimodal network named Dual Stream GRU (DSGRU) model is proposed with training and validation of 316LN stainless steel samples. By incorporating the unrecoverable characteristic of ratcheting behavior into the loss function, there is a significant improvement in the prediction and generalization performance of the DSGRU model. Meanwhile, the multimodal network enables the model to consider material properties at different temperatures. Through sufficient constitutive simulation samples, the DSGRU model with optimal architecture is well-trained and transferred to small sample experimental samples with fine-tuning method. Whether in pre-training or transfer learning processes, the physics-informed loss function ensures the physical consistency of predicted results.
{"title":"Unified prediction of uniaxial ratcheting deformation at elevated temperatures with physics-informed multimodal network","authors":"Zhen Yu, Xingyue Sun, Ruisi Xing, Xu Chen","doi":"10.1016/j.ijplas.2025.104275","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104275","url":null,"abstract":"The ratcheting behavior of plastic deformation accumulation under asymmetric loading poses significant risks to the safe service of engineering structures. For accurate prediction of the ratcheting behavior of the material, a physics-informed multimodal network named Dual Stream GRU (DSGRU) model is proposed with training and validation of 316LN stainless steel samples. By incorporating the unrecoverable characteristic of ratcheting behavior into the loss function, there is a significant improvement in the prediction and generalization performance of the DSGRU model. Meanwhile, the multimodal network enables the model to consider material properties at different temperatures. Through sufficient constitutive simulation samples, the DSGRU model with optimal architecture is well-trained and transferred to small sample experimental samples with fine-tuning method. Whether in pre-training or transfer learning processes, the physics-informed loss function ensures the physical consistency of predicted results.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"63 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417283","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}
Ultrafine elongated grain (UFEG) steel, characterized by its unique multi-level and multi-scale laminated heterogeneous structure, shows considerable promise in addressing the challenge of balancing high strength and toughness in metallic materials. In this work, we develop a coupled nonlocal crystal plasticity and damage phase field model. We derived the dislocation flux term from this model to introduce geometrically necessary dislocation (GND) and back stress to reflect the heterogeneous deformation of the material, and corrected the critical plastic work density term based on the relationship between grain boundary misorientation and grain boundary energy to investigate the strengthening and softening mechanisms of medium carbon steel with UFEG structure under uniaxial tensile deformation. Simulation results indicate that the strengthening effects of GNDs and back stress are closely linked to the material's initial dislocation density and grain size. Higher initial dislocation densities and larger grain sizes limit these effects. Moreover, a higher grain aspect ratio enhances the strengthening effect of GNDs. Different textures significantly affect the tensile properties of the material. The experimentally obtained <110>//RD fiber texture provides some strengthening effect, but there remains a gap compared to the ideal fiber texture. Damage initiates in the elongated grains, but the equiaxed grains help slow its progression. High-angle grain boundaries promote intergranular damage, which restricts the spread of intragranular damage. These boundaries are also critical in the formation of delamination cracks within the BCC material. These insights provide a foundation for understanding the role of grain morphology and GND density in the deformation and failure mechanisms of dual-heterostructured medium carbon steels, offering potential guidance for optimizing microstructure design in these specific material systems.
{"title":"Nonlocal crystal plasticity and damage modeling of dual-heterostructured steel for strengthening and failure analysis","authors":"Shaorong Liu, Yukai Xiong, Jianfeng Zhao, Baoxi Liu, Wenwang Wu, Xu Zhang","doi":"10.1016/j.ijplas.2025.104270","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104270","url":null,"abstract":"Ultrafine elongated grain (UFEG) steel, characterized by its unique multi-level and multi-scale laminated heterogeneous structure, shows considerable promise in addressing the challenge of balancing high strength and toughness in metallic materials. In this work, we develop a coupled nonlocal crystal plasticity and damage phase field model. We derived the dislocation flux term from this model to introduce geometrically necessary dislocation (GND) and back stress to reflect the heterogeneous deformation of the material, and corrected the critical plastic work density term based on the relationship between grain boundary misorientation and grain boundary energy to investigate the strengthening and softening mechanisms of medium carbon steel with UFEG structure under uniaxial tensile deformation. Simulation results indicate that the strengthening effects of GNDs and back stress are closely linked to the material's initial dislocation density and grain size. Higher initial dislocation densities and larger grain sizes limit these effects. Moreover, a higher grain aspect ratio enhances the strengthening effect of GNDs. Different textures significantly affect the tensile properties of the material. The experimentally obtained <110>//RD fiber texture provides some strengthening effect, but there remains a gap compared to the ideal fiber texture. Damage initiates in the elongated grains, but the equiaxed grains help slow its progression. High-angle grain boundaries promote intergranular damage, which restricts the spread of intragranular damage. These boundaries are also critical in the formation of delamination cracks within the BCC material. These insights provide a foundation for understanding the role of grain morphology and GND density in the deformation and failure mechanisms of dual-heterostructured medium carbon steels, offering potential guidance for optimizing microstructure design in these specific material systems.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"79 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417323","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}
To meeting the double demands of structural weight reduction and performance improvement of aerospace vehicle, conventional high-temperature titanium alloys or titanium matrix composites (TMCs) are encountering a huge challenge that the room-temperature ductility will be inevitably deteriorated in pursuit of enhancing the elevated high-temperature strength. The present work proposes a feasible strategy for resolving this contradiction by constructing a novel bimodal architecture and introducing the multiscale reinforcements of microsized TiB whiskers and micro/nanosized Y2O3 particles. The unique bimodal microstructure consists of primary microsized αp/β lath clusters and micro/nano basketweave-like structure composing of αp, secondary nanosized αs and β laths. It is noteworthy that the bimodal (TiB+Y2O3)/Ti composite exhibits excellent mechanical properties with the ultimate tensile strength (UTS) of 1318 MPa with the total elongation to failure (EL) of 10.5 % at room temperature, and UTS of 934 MPa with EL of 23 % at 600 °C, far higher that of the reported 600 °C high temperature titanium alloys or TMCs. In-situ investigations indicate the postponed strain localization, the activated extra <c+a> dislocations within αp laths, and the heterogeneous deformation induced (HDI) hardening caused by the unique bimodal microstructure, synergistically promoted the ductility of bimodal (TiB+Y2O3)/Ti composite. While the strength enhancement at room temperature and 600 °C is attributed to the synergistic strengthening effect of nanosized αs, microsized TiB whiskers and micro/nanosized Y2O3 particles and HDI strengthening. These findings provide a new insight for improving mechanical properties of metal matrix composites.
{"title":"Simultaneously enhancing room-temperature strength-ductility synergy and high-temperature performance of titanium matrix composites via building a unique bimodal architecture with multi-scale reinforcements","authors":"Yuanyuan Zhang, Xiping Cui, Lingfei Chen, Naonao Gao, Xuanchang Zhang, Zhiqi Wang, Guanghui Cong, Xiangxin Zhai, Jiawei Luo, Yifan Zhang, Junfeng Chen, Lin Geng, Lujun Huang","doi":"10.1016/j.ijplas.2025.104283","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104283","url":null,"abstract":"To meeting the double demands of structural weight reduction and performance improvement of aerospace vehicle, conventional high-temperature titanium alloys or titanium matrix composites (TMCs) are encountering a huge challenge that the room-temperature ductility will be inevitably deteriorated in pursuit of enhancing the elevated high-temperature strength. The present work proposes a feasible strategy for resolving this contradiction by constructing a novel bimodal architecture and introducing the multiscale reinforcements of microsized TiB whiskers and micro/nanosized Y<sub>2</sub>O<sub>3</sub> particles. The unique bimodal microstructure consists of primary microsized α<sub>p</sub>/β lath clusters and micro/nano basketweave-like structure composing of α<sub>p</sub>, secondary nanosized α<sub>s</sub> and β laths. It is noteworthy that the bimodal (TiB+Y<sub>2</sub>O<sub>3</sub>)/Ti composite exhibits excellent mechanical properties with the ultimate tensile strength (UTS) of 1318 MPa with the total elongation to failure (EL) of 10.5 % at room temperature, and UTS of 934 MPa with EL of 23 % at 600 °C, far higher that of the reported 600 °C high temperature titanium alloys or TMCs. In-situ investigations indicate the postponed strain localization, the activated extra <c+a> dislocations within α<sub>p</sub> laths, and the heterogeneous deformation induced (HDI) hardening caused by the unique bimodal microstructure, synergistically promoted the ductility of bimodal (TiB+Y<sub>2</sub>O<sub>3</sub>)/Ti composite. While the strength enhancement at room temperature and 600 °C is attributed to the synergistic strengthening effect of nanosized α<sub>s</sub>, microsized TiB whiskers and micro/nanosized Y<sub>2</sub>O<sub>3</sub> particles and HDI strengthening. These findings provide a new insight for improving mechanical properties of metal matrix composites.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"17 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417281","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 : 2025-02-15DOI: 10.1016/j.ijplas.2025.104273
Rafał Schmidt , Elwira Schmidt , Błażej Skoczeń
Fracture is one of the key issues for integrity of structures made of metastable materials operating at extremely low temperatures. A broad class of these materials, in particular the austenitic stainless steels, behave in a ductile way when strained near absolute zero, showing the evidence of ductile fracture. The stainless steels exhibit at very low temperatures metastable behaviour, consisting in the plastic strain induced fcc-bcc phase transformation, leading to generation of two-phase continuum composed of austenitic matrix and martensitic islands. As the classical models of fracture do not include the phase transformation, there is a clear need to extend the description of fracture to multiphase materials. The present model refers to the Hutchinson solution for the stress and strain fields in front of a macrocrack, obtained in the framework of the Hencky–Ilyushin (H–I) deformation theory. Based on this solution, a model including the plastic strain induced phase transformation is developed, and a closed form analytical solution including the distribution of the secondary phase ahead of the crack tip is presented. Moreover, the analytical solution is cross checked with the experimental data obtained for notched specimens, loaded in liquid helium (4.2K) until fracture. Evidence for accumulation of secondary phase along the macrocrack trajectory is shown. The microscopic observations, performed by means of a scanning electron microscope including EBSD, show significant microstructure evolution as well as decreasing martensite content when moving away from the crack tip. A fairly good agreement between the analytical model and experimental data was obtained, indicating the usefulness of the analytical solution.
{"title":"Fracture of metastable materials near absolute zero","authors":"Rafał Schmidt , Elwira Schmidt , Błażej Skoczeń","doi":"10.1016/j.ijplas.2025.104273","DOIUrl":"10.1016/j.ijplas.2025.104273","url":null,"abstract":"<div><div>Fracture is one of the key issues for integrity of structures made of metastable materials operating at extremely low temperatures. A broad class of these materials, in particular the austenitic stainless steels, behave in a ductile way when strained near absolute zero, showing the evidence of ductile fracture. The stainless steels exhibit at very low temperatures metastable behaviour, consisting in the plastic strain induced fcc-bcc phase transformation, leading to generation of two-phase continuum composed of austenitic matrix and martensitic islands. As the classical models of fracture do not include the phase transformation, there is a clear need to extend the description of fracture to multiphase materials. The present model refers to the Hutchinson solution for the stress and strain fields in front of a macrocrack, obtained in the framework of the Hencky–Ilyushin (H–I) deformation theory. Based on this solution, a model including the plastic strain induced phase transformation is developed, and a closed form analytical solution including the distribution of the secondary phase ahead of the crack tip is presented. Moreover, the analytical solution is cross checked with the experimental data obtained for notched specimens, loaded in liquid helium (4.2<span><math><mspace></mspace></math></span>K) until fracture. Evidence for accumulation of secondary phase along the macrocrack trajectory is shown. The microscopic observations, performed by means of a scanning electron microscope including EBSD, show significant microstructure evolution as well as decreasing martensite content when moving away from the crack tip. A fairly good agreement between the analytical model and experimental data was obtained, indicating the usefulness of the analytical solution.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104273"},"PeriodicalIF":9.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417282","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 : 2025-02-14DOI: 10.1016/j.ijplas.2025.104267
S. Zhou, M. Ben Bettaieb, F. Abed-Meraim
A new crystal plasticity finite element (CPFE) approach is developed to predict the mechanical behavior and ductility limits of thin metal sheets. Within this approach, a representative volume element (RVE) is chosen to accurately capture the mechanical characteristics of these metal sheets. This approach uses the periodic homogenization multiscale scheme to ensure the transition between the RVE and single crystal scales. At the single crystal scale, the mechanical behavior is modeled as elastoplastic within the finite strain framework. The plastic flow is governed by a modified version of the Schmid law, which incorporates the effects of damage on the evolution of microscopic mechanical variables. The damage behavior is modeled using the framework of Continuum Damage Mechanics (CDM), introducing a scalar microscopic damage variable at the level of each crystallographic slip system (CSS). The evolution law of this damage variable is derived from thermodynamic forces, resulting in deviations from the normality rule in microscopic plastic flow. This coupling of damage and elastoplastic behavior leads to a highly nonlinear set of constitutive equations. To solve these equations, an efficient return-mapping algorithm is developed and implemented in the ABAQUS/Standard finite element software via a user-defined material subroutine (UMAT). At the macroscopic scale, the onset of localized necking is predicted by the Rice bifurcation theory. The proposed damage-coupled single crystal model and its integration scheme are validated through several numerical simulations. The analysis extensively explores the impact of microstructural and damage parameters on the mechanical behavior and ductility limits of both single crystals and polycrystalline aggregates. The numerical results indicate that both of the mechanical behavior and ductility limits are significantly influenced by the microscopic damage and deviations from normal plastic flow rule.
{"title":"A crystal plasticity-damage coupled finite element framework for predicting mechanical behavior and ductility limits of thin metal sheets","authors":"S. Zhou, M. Ben Bettaieb, F. Abed-Meraim","doi":"10.1016/j.ijplas.2025.104267","DOIUrl":"10.1016/j.ijplas.2025.104267","url":null,"abstract":"<div><div>A new crystal plasticity finite element (CPFE) approach is developed to predict the mechanical behavior and ductility limits of thin metal sheets. Within this approach, a representative volume element (RVE) is chosen to accurately capture the mechanical characteristics of these metal sheets. This approach uses the periodic homogenization multiscale scheme to ensure the transition between the RVE and single crystal scales. At the single crystal scale, the mechanical behavior is modeled as elastoplastic within the finite strain framework. The plastic flow is governed by a modified version of the Schmid law, which incorporates the effects of damage on the evolution of microscopic mechanical variables. The damage behavior is modeled using the framework of Continuum Damage Mechanics (CDM), introducing a scalar microscopic damage variable at the level of each crystallographic slip system (CSS). The evolution law of this damage variable is derived from thermodynamic forces, resulting in deviations from the normality rule in microscopic plastic flow. This coupling of damage and elastoplastic behavior leads to a highly nonlinear set of constitutive equations. To solve these equations, an efficient return-mapping algorithm is developed and implemented in the ABAQUS/Standard finite element software via a user-defined material subroutine (UMAT). At the macroscopic scale, the onset of localized necking is predicted by the Rice bifurcation theory. The proposed damage-coupled single crystal model and its integration scheme are validated through several numerical simulations. The analysis extensively explores the impact of microstructural and damage parameters on the mechanical behavior and ductility limits of both single crystals and polycrystalline aggregates. The numerical results indicate that both of the mechanical behavior and ductility limits are significantly influenced by the microscopic damage and deviations from normal plastic flow rule.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104267"},"PeriodicalIF":9.4,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417678","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 : 2025-02-13DOI: 10.1016/j.ijplas.2025.104274
Wei Li , Alfonso H.W. Ngan , Yuqi Zhang
Complex concentrated alloys (CCAs) differ from pure metals and conventional dilute alloys in that the multiple constituent elements are prone to develop special local atomic environments (LAEs). Due to the complexity and spatial variability of the LAEs, the resistance that they offer to travelling dislocations cannot be determined a priori by conventional strengthening theories. In this work, molecular dynamics (MD) simulations of a prototypic CCA of NiCoCr were used to generate data for dislocation features that may potentially affect dislocation resistance. Extensive analysis of these features via their Pearson correlation coefficients with dislocation velocity and ablation studies using light gradient-boosting machine learning (ML) models show that (i) the local planar fault energy (PFE), (ii) local gradient of the PFE, and (iii) dislocation core width, while all prime factors for dislocation resistance, do not have strongly linear correlation with the dislocation velocity. However, reasonably high prediction accuracy (>80 %) is achieved when all three factors are included in the ML model. Furthermore, lattice distortion, a much-discussed strengthening factor for CCAs in the literature, is also not strongly linearly correlated and its effect can be well represented by the PFE. These results indicate that CCA strength is governed not by individual dislocation-resistance factors, but a synergistic combination of these factors that goes beyond any a priori assumption. This work highlights the complexity in the nature of CCA strength, and the suitability and success of machine learning as an a posteriori approach for understanding it.
{"title":"Machine-learning local resistive environments of dislocations in complex concentrated alloys from data generated by molecular dynamics simulations","authors":"Wei Li , Alfonso H.W. Ngan , Yuqi Zhang","doi":"10.1016/j.ijplas.2025.104274","DOIUrl":"10.1016/j.ijplas.2025.104274","url":null,"abstract":"<div><div>Complex concentrated alloys (CCAs) differ from pure metals and conventional dilute alloys in that the multiple constituent elements are prone to develop special local atomic environments (LAEs). Due to the complexity and spatial variability of the LAEs, the resistance that they offer to travelling dislocations cannot be determined <em>a priori</em> by conventional strengthening theories. In this work, molecular dynamics (MD) simulations of a prototypic CCA of NiCoCr were used to generate data for dislocation features that may potentially affect dislocation resistance. Extensive analysis of these features via their Pearson correlation coefficients with dislocation velocity and ablation studies using light gradient-boosting machine learning (ML) models show that (i) the local planar fault energy (PFE), (ii) local gradient of the PFE, and (iii) dislocation core width, while all prime factors for dislocation resistance, do not have strongly linear correlation with the dislocation velocity. However, reasonably high prediction accuracy (>80 %) is achieved when all three factors are included in the ML model. Furthermore, lattice distortion, a much-discussed strengthening factor for CCAs in the literature, is also not strongly linearly correlated and its effect can be well represented by the PFE. These results indicate that CCA strength is governed not by individual dislocation-resistance factors, but a synergistic combination of these factors that goes beyond any <em>a priori</em> assumption. This work highlights the complexity in the nature of CCA strength, and the suitability and success of machine learning as an <em>a posteriori</em> approach for understanding it.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104274"},"PeriodicalIF":9.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417680","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 : 2025-02-07DOI: 10.1016/j.ijplas.2025.104272
Sihao Zou , Chunyu Dong , Xiaodong Tan , Zhiyuan Liang , Weizong Bao , Binbin He , Wenjun Lu
The design of dual-phase high-entropy alloys (HEAs) often involves extensive alloying, which can lead to the formation of topologically close-packed (TCP) phases, significantly reducing tensile ductility. Balancing the high hardness of TCP phases while minimizing their embrittling effects is crucial for developing high-performance HEAs. This study, which focuses on the brittle sigma phase, proposes an innovative heterogeneous structural coupling design strategy that simultaneously enhances the strengthening effect of the sigma phase while minimizing its embrittlement role. A (FeCoCrNi)90Al10 HEA with sigma phase is employed as the model material, where a bimodal grain heterogeneous structure is achieved through a short-term high-temperature annealing process at 850 °C for 5 min. A small amount of sigma phase precipitates (∼0.8 vol.%) in the recrystallization (RX) region, modulating the hardness difference between the RX and non-recrystallized (NRX) regions. This induces significant heterogeneous deformation-induced (HDI) stress, while promoting coordinated deformation between regions, thereby triggering continuous work hardening and plastic deformation. As a result, the HEA exhibits an exceptional combination of high strength (1412 MPa) and ductility (14.9 %). The underlying deformation mechanism involves strain hardening driven by HDI stress, which strengthens the RX region and minimizes local strain mismatch between the sigma phase and the FCC matrix, suppressing the nucleation and propagation of interfacial cracks. The present approach presents a promising pathway for co-designing strength and ductility in metallic materials susceptible to TCP phase formation.
{"title":"Mitigating embrittlement of sigma phase in dual-phase high-entropy alloys through heterostructure design","authors":"Sihao Zou , Chunyu Dong , Xiaodong Tan , Zhiyuan Liang , Weizong Bao , Binbin He , Wenjun Lu","doi":"10.1016/j.ijplas.2025.104272","DOIUrl":"10.1016/j.ijplas.2025.104272","url":null,"abstract":"<div><div>The design of dual-phase high-entropy alloys (HEAs) often involves extensive alloying, which can lead to the formation of topologically close-packed (TCP) phases, significantly reducing tensile ductility. Balancing the high hardness of TCP phases while minimizing their embrittling effects is crucial for developing high-performance HEAs. This study, which focuses on the brittle sigma phase, proposes an innovative heterogeneous structural coupling design strategy that simultaneously enhances the strengthening effect of the sigma phase while minimizing its embrittlement role. A (FeCoCrNi)<sub>90</sub>Al<sub>10</sub> HEA with sigma phase is employed as the model material, where a bimodal grain heterogeneous structure is achieved through a short-term high-temperature annealing process at 850 °C for 5 min. A small amount of sigma phase precipitates (∼0.8 vol.%) in the recrystallization (RX) region, modulating the hardness difference between the RX and non-recrystallized (NRX) regions. This induces significant heterogeneous deformation-induced (HDI) stress, while promoting coordinated deformation between regions, thereby triggering continuous work hardening and plastic deformation. As a result, the HEA exhibits an exceptional combination of high strength (1412 MPa) and ductility (14.9 %). The underlying deformation mechanism involves strain hardening driven by HDI stress, which strengthens the RX region and minimizes local strain mismatch between the sigma phase and the FCC matrix, suppressing the nucleation and propagation of interfacial cracks. The present approach presents a promising pathway for co-designing strength and ductility in metallic materials susceptible to TCP phase formation.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104272"},"PeriodicalIF":9.4,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143367238","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 : 2025-02-06DOI: 10.1016/j.ijplas.2025.104271
Nilesh Kumar , Franz Miller Branco Ferraz , Ricardo Henrique Buzolin , Esmaeil Shahryari , Maria C. Poletti , Surya D. Yadav
This research presents a dislocation-based hot deformation model to address a nickel-based superalloy's flow stress response and discontinuous dynamic recrystallization (DDRX) behavior. The developed model can predict the flow curves and subsequent microstructure evolutions during the hot deformation. The evolution of microstructure-reliant internal variables was predicted and validated thoroughly. Furthermore, the influence of strain rate and temperature on the glide and climb velocities have also been discussed to reveal more insights into the microstructural development. Dislocation density and DDRX fraction predicted from the model was compared with dislocation density and DDRX fraction obtained from electron backscattered diffraction (EBSD) measurements with reasonable matching. Higher temperatures and slower strain rates provide favorable conditions for DDRX in this alloy. The importance of this model relies on its prediction capability in terms of flow curve, mobile and immobile dislocation densities, DDRX fraction, grain size and dislocation velocities. Single set of parameters were obtained from twelve experimental curves and rest of the eleven curves were predicted by the model using those parameters. The present research approach is helpful to predict the multiple flow curves along with the corresponding microstructure evolution in LSFE materials.
{"title":"A meso-scale model to predict flow stress and microstructure during hot deformation of IN718WP","authors":"Nilesh Kumar , Franz Miller Branco Ferraz , Ricardo Henrique Buzolin , Esmaeil Shahryari , Maria C. Poletti , Surya D. Yadav","doi":"10.1016/j.ijplas.2025.104271","DOIUrl":"10.1016/j.ijplas.2025.104271","url":null,"abstract":"<div><div>This research presents a dislocation-based hot deformation model to address a nickel-based superalloy's flow stress response and discontinuous dynamic recrystallization (DDRX) behavior. The developed model can predict the flow curves and subsequent microstructure evolutions during the hot deformation. The evolution of microstructure-reliant internal variables was predicted and validated thoroughly. Furthermore, the influence of strain rate and temperature on the glide and climb velocities have also been discussed to reveal more insights into the microstructural development. Dislocation density and DDRX fraction predicted from the model was compared with dislocation density and DDRX fraction obtained from electron backscattered diffraction (EBSD) measurements with reasonable matching. Higher temperatures and slower strain rates provide favorable conditions for DDRX in this alloy. The importance of this model relies on its prediction capability in terms of flow curve, mobile and immobile dislocation densities, DDRX fraction, grain size and dislocation velocities. Single set of parameters were obtained from twelve experimental curves and rest of the eleven curves were predicted by the model using those parameters. The present research approach is helpful to predict the multiple flow curves along with the corresponding microstructure evolution in LSFE materials.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104271"},"PeriodicalIF":9.4,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143192396","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}
The (FeCoNi)86Al7Ti7 medium-entropy alloy (MEA) with varying sizes and fixed volume fraction of coherent L12 precipitates was fabricated, and the effects of precipitation size on mechanical properties at varying strain rates and temperatures were investigated experimentally. An optimum precipitation size for precipitation strengthening can be always observed for the experimental curves under different strain rates and temperatures. The dominant precipitation mechanism under dynamic conditions is found to be transited from the dislocation-shearing mechanism to the Orowan dislocation-looping mechanism with increasing precipitation size. A novel theoretical model was developed to consider the effects of strain rate and temperature on the precipitation shearing strengthening and the Orowan looping strengthening. The predicted precipitation strengthening curves as a function of precipitation size by the newly-developed model are observed to be well consistent with the experimental results under different strain rates and temperatures. The optimum precipitation size for the strongest precipitation strengthening is found to be strain-rate and temperature dependent, and shift to higher values with increasing strain rate and decreasing temperature, as predicted by the theoretical model and validated by the experimental results.
{"title":"Strain-rate and temperature dependent optimum precipitation sizes for strengthening in medium-entropy alloys","authors":"Ziyi Yuan , Cen Chen , Xu Zhang , Lingling Zhou , Xiaolei Wu , Fuping Yuan","doi":"10.1016/j.ijplas.2025.104268","DOIUrl":"10.1016/j.ijplas.2025.104268","url":null,"abstract":"<div><div>The (FeCoNi)<sub>86</sub>Al<sub>7</sub>Ti<sub>7</sub> medium-entropy alloy (MEA) with varying sizes and fixed volume fraction of coherent L1<sub>2</sub> precipitates was fabricated, and the effects of precipitation size on mechanical properties at varying strain rates and temperatures were investigated experimentally. An optimum precipitation size for precipitation strengthening can be always observed for the experimental curves under different strain rates and temperatures. The dominant precipitation mechanism under dynamic conditions is found to be transited from the dislocation-shearing mechanism to the Orowan dislocation-looping mechanism with increasing precipitation size. A novel theoretical model was developed to consider the effects of strain rate and temperature on the precipitation shearing strengthening and the Orowan looping strengthening. The predicted precipitation strengthening curves as a function of precipitation size by the newly-developed model are observed to be well consistent with the experimental results under different strain rates and temperatures. The optimum precipitation size for the strongest precipitation strengthening is found to be strain-rate and temperature dependent, and shift to higher values with increasing strain rate and decreasing temperature, as predicted by the theoretical model and validated by the experimental results.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"187 ","pages":"Article 104268"},"PeriodicalIF":9.4,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258673","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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