Metastable high entropy alloys (HEAs) provide an exceptional combination of strength and ductility by the synergistic operation of slip, twinning, and transformation; however, their fracture behaviour remains unexplored. In the present investigation, tensile and elastic-plastic fracture toughness tests with a 2D digital image correlation setup were carried out for different microstructural states of Fe42Mn28Co10Cr15Si5 HEA. Finite element analysis (FEA) coupled with combinatorial site-specific electron backscatter diffraction helps in developing a meso and micro scale mechanistic understanding of the extrinsic and intrinsic toughening processes. The calculated J-integral and plastic zone size using FEA simulations were corroborated with experimental results. The crack growth resistance (J-R) curve was evaluated across three distinct processing conditions: hot rolled (HR), 1 h annealed at 1173 K (AN1173), and 4 h annealed at 1373 K (AN1373). The HR material exhibited higher strength (yield strength = 630 ± 8 MPa), while the AN1373 demonstrated highest ductility (0.74 ± 0.04). The mode I plane strain fracture toughness was highest for the AN1373 (125.4 ± 15.8 MPa.m0.5) and lowest for the AN1173 (46.3 ± 7.4 MPa.m0.5). The Cr-rich sigma phase at grain boundaries in the HR and AN1173 led to pronounced intergranular fracture, resulting in lower fracture toughness and plasticity. The multiple variants of martensite in the AN1373 microstructural state, results in refined microstructure by interactions of transformation variants and dislocations that enhance the strength, ductility, and crack tip plasticity. The findings underscore the significant impact of intrinsic toughening on the fracture and deformation behaviour of the Fe42Mn28Co10Cr15Si5 HEA.
{"title":"Tailoring fracture resistance of a metastable Fe42Mn28Co10Cr15Si5 high entropy alloy by intrinsic toughening","authors":"Manoj Yadav, Niraj Nayan, Krishanu Biswas, N.P. Gurao","doi":"10.1016/j.ijplas.2025.104315","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104315","url":null,"abstract":"Metastable high entropy alloys (HEAs) provide an exceptional combination of strength and ductility by the synergistic operation of slip, twinning, and transformation; however, their fracture behaviour remains unexplored. In the present investigation, tensile and elastic-plastic fracture toughness tests with a 2D digital image correlation setup were carried out for different microstructural states of Fe<sub>42</sub>Mn<sub>28</sub>Co<sub>10</sub>Cr<sub>15</sub>Si<sub>5</sub> HEA. Finite element analysis (FEA) coupled with combinatorial site-specific electron backscatter diffraction helps in developing a meso and micro scale mechanistic understanding of the extrinsic and intrinsic toughening processes. The calculated J-integral and plastic zone size using FEA simulations were corroborated with experimental results. The crack growth resistance (J-R) curve was evaluated across three distinct processing conditions: hot rolled (HR), 1 h annealed at 1173 K (AN1173), and 4 h annealed at 1373 K (AN1373). The HR material exhibited higher strength (yield strength = 630 ± 8 MPa), while the AN1373 demonstrated highest ductility (0.74 ± 0.04). The mode I plane strain fracture toughness was highest for the AN1373 (125.4 ± 15.8 MPa.m<sup>0.5</sup>) and lowest for the AN1173 (46.3 ± 7.4 MPa.m<sup>0.5</sup>). The Cr-rich sigma phase at grain boundaries in the HR and AN1173 led to pronounced intergranular fracture, resulting in lower fracture toughness and plasticity. The multiple variants of martensite in the AN1373 microstructural state, results in refined microstructure by interactions of transformation variants and dislocations that enhance the strength, ductility, and crack tip plasticity. The findings underscore the significant impact of intrinsic toughening on the fracture and deformation behaviour of the Fe<sub>42</sub>Mn<sub>28</sub>Co<sub>10</sub>Cr<sub>15</sub>Si<sub>5</sub> HEA.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"5 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660564","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 : 2025-03-19DOI: 10.1016/j.ijplas.2025.104312
Jiachen Hu, Bo Xu, Junyuan Xiong, Chao Yu, Guozheng Kang
In this work, an improved crystal plasticity coupled twinning phase field is developed by introducing a hyperbolic hardening function describing the hardening resulting from dislocation slipping interactions. This model effectively captures the complex interactions of multiple plasticity mechanisms in non-textured (NT) and basal-textured (BT) polycrystalline Mg alloys under monotonic and tension-compression cyclic loadings. The results indicate that NT polycrystalline Mg alloy exhibit multi-mode plastic deformation combining basal/non-basal slipping and twinning due to random grain orientations, whereas BT polycrystalline Mg alloys predominantly activate one or two plastic deformation modes including the basal slipping, and the texture angle α (characterized the statistical average properties of the grain orientations) modulates plastic mechanism with selective sensitivity. Cyclic loading reveals tension-compression symmetry in NT and BT (α = 45°) systems, but asymmetry in BT (α = 0°/90°) due to alternating plastic mechanisms. De-twinning-induced nonlinear unloading emerges in both NT and BT polycrystalline systems, and inhomogeneous stress near grain boundaries and twin intersection regions impedes complete de-twinning, accumulating residual twins that facilitate subsequent nucleation. Dislocation slipping, particularly the basal slipping, accommodates strain incompatibility at grain boundaries and around twins, and demonstrates dual roles on twinning. Neighboring grain interactions induce anomalous local deformation inconsistent with the Schmid's law. These findings establish microstructure-property relationships supporting the development of texture-based strengthening-toughening strategies for Mg alloys.
{"title":"Deformation Mechanism of Non-textured and Basal-textured Polycrystalline Mg Alloys: A Coupled Crystal Plasticity-Twinning Phase Field Simulation","authors":"Jiachen Hu, Bo Xu, Junyuan Xiong, Chao Yu, Guozheng Kang","doi":"10.1016/j.ijplas.2025.104312","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104312","url":null,"abstract":"In this work, an improved crystal plasticity coupled twinning phase field is developed by introducing a hyperbolic hardening function describing the hardening resulting from dislocation slipping interactions. This model effectively captures the complex interactions of multiple plasticity mechanisms in non-textured (NT) and basal-textured (BT) polycrystalline Mg alloys under monotonic and tension-compression cyclic loadings. The results indicate that NT polycrystalline Mg alloy exhibit multi-mode plastic deformation combining basal/non-basal slipping and twinning due to random grain orientations, whereas BT polycrystalline Mg alloys predominantly activate one or two plastic deformation modes including the basal slipping, and the texture angle <em>α</em> (characterized the statistical average properties of the grain orientations) modulates plastic mechanism with selective sensitivity. Cyclic loading reveals tension-compression symmetry in NT and BT (<em>α</em> = 45°) systems, but asymmetry in BT (<em>α</em> = 0°/90°) due to alternating plastic mechanisms. De-twinning-induced nonlinear unloading emerges in both NT and BT polycrystalline systems, and inhomogeneous stress near grain boundaries and twin intersection regions impedes complete de-twinning, accumulating residual twins that facilitate subsequent nucleation. Dislocation slipping, particularly the basal slipping, accommodates strain incompatibility at grain boundaries and around twins, and demonstrates dual roles on twinning. Neighboring grain interactions induce anomalous local deformation inconsistent with the Schmid's law. These findings establish microstructure-property relationships supporting the development of texture-based strengthening-toughening strategies for Mg alloys.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"34 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660548","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 : 2025-03-19DOI: 10.1016/j.ijplas.2025.104314
Noah J. Schmelzer, Evan J. Lieberman, Nan Chen, Curt A. Bronkhorst
A study of the partitioning of external power into stress power, stored defect energy, thermal energy, and inertia during dynamic void growth is presented. An alternative form for a classical thick-walled sphere governing equation stemming from a local power balance including energetic cost of free surface creation is proposed. The importance of proper energy accounting in the context of dynamic ductile damage is discussed. An isotropic thermodynamically consistent thermomechanical dislocation density-based plasticity model is presented and compared against experimental data for high-purity BCC tantalum. This model accounts for plastic power partitioning to stored defect energy and thermal energy with evolving Taylor-Quinney coefficient. The plasticity model is used to perform a suite of thick-walled sphere calculations spanning a wide range of deformation rates and initial temperatures. Thick-walled sphere geometry and initial porosity are based on post-mortem metallographic analysis of void size and spacing in high-purity tantalum. Stress measures of interest as well as quantities provided by enforced thermodynamic consistency are evaluated across the radius of thick-walled sphere calculations as a function of strain rate and temperature. Agglomeration of the resulting 35 thick-walled sphere simulations provides a database for statistical evaluation. Analysis using information theory yields a simple reduced order functional form for the total thick-walled sphere stress power in terms of surface quantities and solid volume. Validation of the found functional form is performed for five arbitrary loading curves showing good agreement. Implications for the local power balance evolution equation are examined. Suitability of the resulting void governing equation for use in continuum-scale dynamic ductile damage models is discussed.
{"title":"Quantifying power partitioning during void growth for dynamic mechanical loading in reduced form","authors":"Noah J. Schmelzer, Evan J. Lieberman, Nan Chen, Curt A. Bronkhorst","doi":"10.1016/j.ijplas.2025.104314","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104314","url":null,"abstract":"A study of the partitioning of external power into stress power, stored defect energy, thermal energy, and inertia during dynamic void growth is presented. An alternative form for a classical thick-walled sphere governing equation stemming from a local power balance including energetic cost of free surface creation is proposed. The importance of proper energy accounting in the context of dynamic ductile damage is discussed. An isotropic thermodynamically consistent thermomechanical dislocation density-based plasticity model is presented and compared against experimental data for high-purity BCC tantalum. This model accounts for plastic power partitioning to stored defect energy and thermal energy with evolving Taylor-Quinney coefficient. The plasticity model is used to perform a suite of thick-walled sphere calculations spanning a wide range of deformation rates and initial temperatures. Thick-walled sphere geometry and initial porosity are based on post-mortem metallographic analysis of void size and spacing in high-purity tantalum. Stress measures of interest as well as quantities provided by enforced thermodynamic consistency are evaluated across the radius of thick-walled sphere calculations as a function of strain rate and temperature. Agglomeration of the resulting 35 thick-walled sphere simulations provides a database for statistical evaluation. Analysis using information theory yields a simple reduced order functional form for the total thick-walled sphere stress power in terms of surface quantities and solid volume. Validation of the found functional form is performed for five arbitrary loading curves showing good agreement. Implications for the local power balance evolution equation are examined. Suitability of the resulting void governing equation for use in continuum-scale dynamic ductile damage models is discussed.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"56 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660522","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 : 2025-03-17DOI: 10.1016/j.ijplas.2025.104310
Tianle Li, Ning Xu, Xiang Wu, Jiaobao Liu, Xiaochun Liu, Xifeng Li
Understanding the relationship between deformation behaviors and mechanisms is significant for the processing and application of metastable β titanium alloys. Here we aim to investigate and evaluate the abnormal yield strength and strain softening of a Ti-15.1Mo-2.77Nb-3.1Al-0.21Si alloy at room temperature. This alloy exhibits a high yield strength of 970 MPa, followed by the continuous stress drop behavior in the entire engineering strains (or true strains of 0.018 ∼ 0.056). Digital image correlation (DIC) reveals that the flow stress drop results from local strain softening associated with a local increase in strain rate, instead of Lüders strain. The pinning between dislocations and Si atoms as well as other interstitial atoms at and near grain boundaries is mainly responsible for the high yield strength. Subsequently, dislocations originating from grain boundaries can easily slip in a planar pattern along the {110} <111> slip systems, resulting in a continuous stress drop. In addition, both the low density of dislocations within β grains and large grain size also provide favorable conditions for dislocation slip over a long distance. This study reveals the mechanisms of both high yield strength and strain softening in the metastable β Ti alloys.
{"title":"Abnormal high yield strength and strain softening in a metastable β titanium alloy at room temperature","authors":"Tianle Li, Ning Xu, Xiang Wu, Jiaobao Liu, Xiaochun Liu, Xifeng Li","doi":"10.1016/j.ijplas.2025.104310","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104310","url":null,"abstract":"Understanding the relationship between deformation behaviors and mechanisms is significant for the processing and application of metastable β titanium alloys. Here we aim to investigate and evaluate the abnormal yield strength and strain softening of a Ti-15.1Mo-2.77Nb-3.1Al-0.21Si alloy at room temperature. This alloy exhibits a high yield strength of 970 MPa, followed by the continuous stress drop behavior in the entire engineering strains (or true strains of 0.018 ∼ 0.056). Digital image correlation (DIC) reveals that the flow stress drop results from local strain softening associated with a local increase in strain rate, instead of Lüders strain. The pinning between dislocations and Si atoms as well as other interstitial atoms at and near grain boundaries is mainly responsible for the high yield strength. Subsequently, dislocations originating from grain boundaries can easily slip in a planar pattern along the {110} <111> slip systems, resulting in a continuous stress drop. In addition, both the low density of dislocations within β grains and large grain size also provide favorable conditions for dislocation slip over a long distance. This study reveals the mechanisms of both high yield strength and strain softening in the metastable β Ti alloys.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"196 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639974","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 : 2025-03-17DOI: 10.1016/j.ijplas.2025.104290
Shidong Wang , Wenhua Wu , Yuxuan Zhao , Yue Sun , Chenghao Song , Youyou Zhang , Gang Sha , Zengbao Jiao , Tao Yang , Hao Chen
This study systematically investigates the effects of different annealing treatments before identical aging on precipitation and mechanical properties of an L12-strengthened Fe-rich medium-entropy alloy (Fe-MEA) fabricated by laser powder bed fusion (L-PBF). These treatments result in distinct final microstructures characterized by either discontinuous precipitation (DP) or continuous precipitation (CP) dominance, accompanied by varied mechanical properties. The high-density dislocations and coarse grains induced by L-PBF promote CP. In contrast, the fine grains formed via L-PBF and the reduced dislocation density through annealing enhance DP, leading to grain refinement. The L-PBF Fe-MEA subjected to various post-printing heat treatments also demonstrates acceptable mechanical properties. It is revealed that the stacking fault energy (SFE) of the face-centered cubic (fcc) matrix in the direct-aged sample is sufficiently low to facilitate the formation of deformation-induced twinning and stacking faults (SFs) in both the CP and DP regions, indicating that both regions exhibit good deformation capacity. Additionally, hetero-deformation-induced (HDI) strengthening significantly contributes to the strength of the studied samples. In the annealing-aged samples, HDI strengthening primarily originates from the heterogeneous distribution of grains and precipitates (fine grains containing DP and coarse grain including CP). In contrast, in the direct-aged sample, HDI strengthening is attributed not only to the heterogeneous grains and precipitates but also to the heterogeneous dislocation structure. This work may provide guidance for modulating L12 precipitation behavior and mechanical properties of high/medium-entropy alloys (H/MEAs) fabricated by L-PBF.
{"title":"Modulating L12 precipitation behavior and mechanical properties in an Fe-rich medium-entropy alloy fabricated via laser powder bed fusion","authors":"Shidong Wang , Wenhua Wu , Yuxuan Zhao , Yue Sun , Chenghao Song , Youyou Zhang , Gang Sha , Zengbao Jiao , Tao Yang , Hao Chen","doi":"10.1016/j.ijplas.2025.104290","DOIUrl":"10.1016/j.ijplas.2025.104290","url":null,"abstract":"<div><div>This study systematically investigates the effects of different annealing treatments before identical aging on precipitation and mechanical properties of an L1<sub>2</sub>-strengthened Fe-rich medium-entropy alloy (Fe-MEA) fabricated by laser powder bed fusion (L-PBF). These treatments result in distinct final microstructures characterized by either discontinuous precipitation (DP) or continuous precipitation (CP) dominance, accompanied by varied mechanical properties. The high-density dislocations and coarse grains induced by L-PBF promote CP. In contrast, the fine grains formed via L-PBF and the reduced dislocation density through annealing enhance DP, leading to grain refinement. The L-PBF Fe-MEA subjected to various post-printing heat treatments also demonstrates acceptable mechanical properties. It is revealed that the stacking fault energy (SFE) of the face-centered cubic (fcc) matrix in the direct-aged sample is sufficiently low to facilitate the formation of deformation-induced twinning and stacking faults (SFs) in both the CP and DP regions, indicating that both regions exhibit good deformation capacity. Additionally, hetero-deformation-induced (HDI) strengthening significantly contributes to the strength of the studied samples. In the annealing-aged samples, HDI strengthening primarily originates from the heterogeneous distribution of grains and precipitates (fine grains containing DP and coarse grain including CP). In contrast, in the direct-aged sample, HDI strengthening is attributed not only to the heterogeneous grains and precipitates but also to the heterogeneous dislocation structure. This work may provide guidance for modulating L1<sub>2</sub> precipitation behavior and mechanical properties of high/medium-entropy alloys (H/MEAs) fabricated by L-PBF.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"188 ","pages":"Article 104290"},"PeriodicalIF":9.4,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640988","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 : 2025-03-16DOI: 10.1016/j.ijplas.2025.104308
Fei Shuang, Yucheng Ji, Luca Laurenti, Poulumi Dey
Multi-principal element alloys (MPEAs) are renowned for their enhanced mechanical strength relative to their constituent metals, as evidenced by various experimental techniques such as tension/compression tests and instrumental indentation. Nevertheless, atomistic simulations sometimes produce conflicting results, casting doubt on the consistently superior mechanical properties of MPEAs. In this study, machine-learning interatomic potentials (MLIPs) with first-principles accuracy were developed for body-centered cubic refractory MoNbTaW MPEAs, enabling systematic atomistic simulations under various deformation scenarios. The new MLIPs are supported by a comprehensive dataset encompassing extensive defects, and the established embedded-atom model (EAM) potential was benchmarked against both this dataset and the new MLIP. Simulations covering diverse compositions confirm that both MLIPs and EAM accurately capture the critical strengthening mechanisms in MoNbTaW MPEAs. It is revealed that MPEAs generally exhibit superior mechanical strength compared to their constituent metals in macroscale specimens, primarily due to solid solution strengthening during dislocation motion. However, at the nanoscale—where plasticity is predominantly governed by dislocation nucleation and grain boundary deformation—the constituent metals may outperform MPEAs. A critical length scale is identified above which MPEAs demonstrate enhanced mechanical strength relative to their constituent elements; below this scale, the advantage diminishes, underscoring a significant size-dependent effect that is crucial for optimizing MPEA applications, particularly at the nanoscale.
{"title":"Size-dependent strength superiority in multi-principal element alloys versus constituent metals: insights from machine-learning atomistic simulations","authors":"Fei Shuang, Yucheng Ji, Luca Laurenti, Poulumi Dey","doi":"10.1016/j.ijplas.2025.104308","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104308","url":null,"abstract":"Multi-principal element alloys (MPEAs) are renowned for their enhanced mechanical strength relative to their constituent metals, as evidenced by various experimental techniques such as tension/compression tests and instrumental indentation. Nevertheless, atomistic simulations sometimes produce conflicting results, casting doubt on the consistently superior mechanical properties of MPEAs. In this study, machine-learning interatomic potentials (MLIPs) with first-principles accuracy were developed for body-centered cubic refractory MoNbTaW MPEAs, enabling systematic atomistic simulations under various deformation scenarios. The new MLIPs are supported by a comprehensive dataset encompassing extensive defects, and the established embedded-atom model (EAM) potential was benchmarked against both this dataset and the new MLIP. Simulations covering diverse compositions confirm that both MLIPs and EAM accurately capture the critical strengthening mechanisms in MoNbTaW MPEAs. It is revealed that MPEAs generally exhibit superior mechanical strength compared to their constituent metals in macroscale specimens, primarily due to solid solution strengthening during dislocation motion. However, at the nanoscale—where plasticity is predominantly governed by dislocation nucleation and grain boundary deformation—the constituent metals may outperform MPEAs. A critical length scale is identified above which MPEAs demonstrate enhanced mechanical strength relative to their constituent elements; below this scale, the advantage diminishes, underscoring a significant size-dependent effect that is crucial for optimizing MPEA applications, particularly at the nanoscale.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"24 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143631170","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 : 2025-03-12DOI: 10.1016/j.ijplas.2025.104296
Xiaofeng Dang , Yao Li , Jie Zheng , Luqing Cui , Kaiju Lu , Xiaoqing Liang , Sihai Luo , Guangni Zhou , Yang Jiao , Yihua Dou , Liucheng Zhou , Weifeng He
Shear banding coupled with grain refinement plays a critical role in fracture behavior under dynamic loading and (very) high-cycle fatigue but is rarely observed during low-strain-rate loading. In this study, we report for the first experimental evidence of shear banding mediated fracture mechanism in an electron beam powder bed fusion (EBPBF) fabricated IN738 superalloy upon low-strain-rate (1 × 10−3 s−1) uniaxial tensile loading. The optimized EBPBF process mitigates solidification defects and produces well-aligned columnar grains with a <001> fiber texture along the building direction, achieving superior mechanical properties compared to cast alloys through the synergistic effect of multiple strengthening mechanisms. Notably, the relatively uniform distribution of nano-sized carbides in the EBPBF-fabricated alloys prevents strain-incompatibility cracking caused by coarse carbides in cast alloys and facilitates shear banding mediated transgranular fracture. The shear band, formed due to concentrated plastic deformation along the crack path, is associated with complete grain nanocrystallization and γ′ precipitate fragmentation through intensive dislocations and twinning activities. The formation of shear banding potentially dissipates crack propagation energy and enhances the crack growth resistance. These findings provide new insights into fracture mechanisms and underscore the potential of additive manufacturing for designing damage-tolerant superalloys.
{"title":"Shear banding mediated fracture mechanisms in additively manufactured IN738 superalloys under low-strain-rate loading","authors":"Xiaofeng Dang , Yao Li , Jie Zheng , Luqing Cui , Kaiju Lu , Xiaoqing Liang , Sihai Luo , Guangni Zhou , Yang Jiao , Yihua Dou , Liucheng Zhou , Weifeng He","doi":"10.1016/j.ijplas.2025.104296","DOIUrl":"10.1016/j.ijplas.2025.104296","url":null,"abstract":"<div><div>Shear banding coupled with grain refinement plays a critical role in fracture behavior under dynamic loading and (very) high-cycle fatigue but is rarely observed during low-strain-rate loading. In this study, we report for the first experimental evidence of shear banding mediated fracture mechanism in an electron beam powder bed fusion (EBPBF) fabricated IN738 superalloy upon low-strain-rate (1 × 10<sup>−3</sup> s<sup>−1</sup>) uniaxial tensile loading. The optimized EBPBF process mitigates solidification defects and produces well-aligned columnar grains with a <001> fiber texture along the building direction, achieving superior mechanical properties compared to cast alloys through the synergistic effect of multiple strengthening mechanisms. Notably, the relatively uniform distribution of nano-sized carbides in the EBPBF-fabricated alloys prevents strain-incompatibility cracking caused by coarse carbides in cast alloys and facilitates shear banding mediated transgranular fracture. The shear band, formed due to concentrated plastic deformation along the crack path, is associated with complete grain nanocrystallization and γ′ precipitate fragmentation through intensive dislocations and twinning activities. The formation of shear banding potentially dissipates crack propagation energy and enhances the crack growth resistance. These findings provide new insights into fracture mechanisms and underscore the potential of additive manufacturing for designing damage-tolerant superalloys.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"188 ","pages":"Article 104296"},"PeriodicalIF":9.4,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143599645","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 : 2025-03-12DOI: 10.1016/j.ijplas.2025.104307
Le Bo, Xiaoyu Gao, Wenjing Song, Zhiliang Ning, Jianfei Sun, Alfonso H.W. Ngan, Yongjiang Huang
High-entropy alloys (HEAs) exhibit a wide diversity of crystalline defects for property control. Fabricating HEAs in microfiber forms further enhances property controllability due to intrinsic and extrinsic size effects. In this study, CoCrFeNi high entropy alloy microfibers with 30–100 μm diameters (D) and grain sizes (d) of 2.1–60.6 μm, were obtained through drawing, electric current annealing, and electropolishing, and subjected to uniaxial tensile testing. As D/d > 3, the yield strength obeys the Hall-Petch relation concerning d and a smaller-is-weaker effect or is insensitive to D. When D/d < 3, the yield strength deviates positively from the Hall-Petch relationship with respect to d and a smaller-is-stronger effect to D. The D/d > 3 behavior is due to grain boundary strengthening and surface-grain softening, while the D/d < 3 behavior is driven by reduced dislocation accumulation and size effects influenced by the limited number of grains spanning the diameter. These findings illustrate that in small-diameter microfibers, strengthening and weakening mechanisms intertwine to yield complex size effects, thus offering the potential to tailor the mechanical properties of micro-sized polycrystalline components through grain-size control and external-size adjustment.
{"title":"Size-dependent mechanical behaviors and mechanisms in CoCrFeNi microfibers","authors":"Le Bo, Xiaoyu Gao, Wenjing Song, Zhiliang Ning, Jianfei Sun, Alfonso H.W. Ngan, Yongjiang Huang","doi":"10.1016/j.ijplas.2025.104307","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104307","url":null,"abstract":"High-entropy alloys (HEAs) exhibit a wide diversity of crystalline defects for property control. Fabricating HEAs in microfiber forms further enhances property controllability due to intrinsic and extrinsic size effects. In this study, CoCrFeNi high entropy alloy microfibers with 30–100 μm diameters (<em>D</em>) and grain sizes (<em>d</em>) of 2.1–60.6 μm, were obtained through drawing, electric current annealing, and electropolishing, and subjected to uniaxial tensile testing. As <em>D</em>/<em>d</em> > 3, the yield strength obeys the Hall-Petch relation concerning <em>d</em> and a smaller-is-weaker effect or is insensitive to <em>D</em>. When <em>D</em>/<em>d</em> < 3, the yield strength deviates positively from the Hall-Petch relationship with respect to <em>d</em> and a smaller-is-stronger effect to <em>D</em>. The <em>D</em>/<em>d</em> > 3 behavior is due to grain boundary strengthening and surface-grain softening, while the <em>D</em>/<em>d</em> < 3 behavior is driven by reduced dislocation accumulation and size effects influenced by the limited number of grains spanning the diameter. These findings illustrate that in small-diameter microfibers, strengthening and weakening mechanisms intertwine to yield complex size effects, thus offering the potential to tailor the mechanical properties of micro-sized polycrystalline components through grain-size control and external-size adjustment.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"183 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143608087","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 : 2025-03-11DOI: 10.1016/j.ijplas.2025.104306
Li Cao , Renyi Lu , Zheng Dou , Min Zheng , Xiao Han , Yu Hao , Li Zhang , Jinfang Zhang , Bin Liu , Xiaofeng Li
The formation of intermetallic compound has been widely considered as an effective strengthening approach in Al alloy. Its precipitate dimension is a key factor influencing the mechanical performance. Except for the pinning effect of nanosized precipitate, the contribution of submicron precipitate is also nonnegligible. Therefore, establishing the mechanism framework for the relationship of manufacturing process-precipitate structure-fracture performance is of great significance, which is essential and foundational for optimizing the practical service performance of alloys parts. Herein, by taking the Al-Cu-Ni series alloy (e.g. RR350) as background, the study reveals the microstructure evolution of high-strength submicron Al7Cu4Ni precipitate from fabrication (additive manufacturing-heat treatment) to failure, and its influence mechanism on the fracture behavior. Through the microstructure regulation, a high elongation rate of ∼28.5 % and slightly-deteriorated ultimate tensile strength of ∼305.2 MPa are achieved. The in-situ and ex-situ characterizations are employed to analyze the synergy mechanism of strength-ductility performance. Some novel findings are obtained that the submicron grain-boundary precipitates can interrupt the intergranular crack by influencing the stress status, thus decreasing the crack propagation rate and altering its propagation pathways. The entangled dislocation also presents an obstruction impact on the intragranular crack extension by its hardening effect. Moreover, the submicron Al7Cu4Ni precipitates with high bonding strength can withstand the concentrated stress to maintain a stable structure during alloy fracture, meanwhile present a strengthening effect on α-Al matrix to ameliorate the deterioration of tensile strength. The characterization of dislocation and microcrack evolution, provides direct evidence to the mechanism framework above, and could also provide insights into the strength-ductility coordination for other Al alloys.
{"title":"Understanding the influence of high-strength submicron precipitate on the fracture performance of additively-manufactured aluminum alloy","authors":"Li Cao , Renyi Lu , Zheng Dou , Min Zheng , Xiao Han , Yu Hao , Li Zhang , Jinfang Zhang , Bin Liu , Xiaofeng Li","doi":"10.1016/j.ijplas.2025.104306","DOIUrl":"10.1016/j.ijplas.2025.104306","url":null,"abstract":"<div><div>The formation of intermetallic compound has been widely considered as an effective strengthening approach in Al alloy. Its precipitate dimension is a key factor influencing the mechanical performance. Except for the pinning effect of nanosized precipitate, the contribution of submicron precipitate is also nonnegligible. Therefore, establishing the mechanism framework for the relationship of manufacturing process-precipitate structure-fracture performance is of great significance, which is essential and foundational for optimizing the practical service performance of alloys parts. Herein, by taking the Al-Cu-Ni series alloy (e.g. RR350) as background, the study reveals the microstructure evolution of high-strength submicron Al<sub>7</sub>Cu<sub>4</sub>Ni precipitate from fabrication (additive manufacturing-heat treatment) to failure, and its influence mechanism on the fracture behavior. Through the microstructure regulation, a high elongation rate of ∼28.5 % and slightly-deteriorated ultimate tensile strength of ∼305.2 MPa are achieved. The <em>in-situ</em> and <em>ex-situ</em> characterizations are employed to analyze the synergy mechanism of strength-ductility performance. Some novel findings are obtained that the submicron grain-boundary precipitates can interrupt the intergranular crack by influencing the stress status, thus decreasing the crack propagation rate and altering its propagation pathways. The entangled dislocation also presents an obstruction impact on the intragranular crack extension by its hardening effect. Moreover, the submicron Al<sub>7</sub>Cu<sub>4</sub>Ni precipitates with high bonding strength can withstand the concentrated stress to maintain a stable structure during alloy fracture, meanwhile present a strengthening effect on α-Al matrix to ameliorate the deterioration of tensile strength. The characterization of dislocation and microcrack evolution, provides direct evidence to the mechanism framework above, and could also provide insights into the strength-ductility coordination for other Al alloys.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"188 ","pages":"Article 104306"},"PeriodicalIF":9.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143599778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-09DOI: 10.1016/j.ijplas.2025.104304
X.D. Zan, X. Guo, G.J. Weng
Zirconium (Zr) alloys are widely used as fuel cladding materials in nuclear reactors; however, the formation of hydride precipitates within these alloys during service significantly reduces their ductility. The effects of hydrides on the fracture behavior of Zr alloys, particularly the role of misfit strain induced by hydride precipitation, remains inadequately understood. Additionally, there is a lack of robust mesoscale models to accurately describe the failure mechanisms of hydrogenated Zr alloys. In response, we develop a crystal plasticity coupled phase-field fracture model that accounts for the evolution of dislocation density, the degradation of critical energy release rate, and the coupling effects between plasticity and damage. The model is employed to investigate the effects of misfit strain induced by hydride precipitation, hydride orientation, and hydride volume fraction on the fracture behavior of hydrogenated Zr alloys. The study also explores the underlying microscopic fracture mechanisms in detail. The results demonstrate that the proposed model effectively captures the influences of hydrides on the ductility of Zr alloys. Specifically, an increase in hydride volume fraction leads to a significant reduction in the ductility and toughness of Zr alloys. The microscopic fracture characteristics of hydrogenated Zr alloys differ significantly between those containing circumferential and radial hydrides, resulting in substantially lower ductility and toughness in samples with radial hydrides under the same conditions. Most importantly, our simulations reveal that misfit strain induced by hydride precipitation is an indispensable factor leading to hydrogen embrittlement in Zr alloys. This research provides valuable insights into the failure mechanisms of hydrogenated Zr alloys and offers a powerful tool for accurately modeling their fracture behavior.
{"title":"Simulation of fracture behaviors in hydrogenated zirconium alloys using a crystal plasticity coupled phase-field fracture model","authors":"X.D. Zan, X. Guo, G.J. Weng","doi":"10.1016/j.ijplas.2025.104304","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104304","url":null,"abstract":"Zirconium (Zr) alloys are widely used as fuel cladding materials in nuclear reactors; however, the formation of hydride precipitates within these alloys during service significantly reduces their ductility. The effects of hydrides on the fracture behavior of Zr alloys, particularly the role of misfit strain induced by hydride precipitation, remains inadequately understood. Additionally, there is a lack of robust mesoscale models to accurately describe the failure mechanisms of hydrogenated Zr alloys. In response, we develop a crystal plasticity coupled phase-field fracture model that accounts for the evolution of dislocation density, the degradation of critical energy release rate, and the coupling effects between plasticity and damage. The model is employed to investigate the effects of misfit strain induced by hydride precipitation, hydride orientation, and hydride volume fraction on the fracture behavior of hydrogenated Zr alloys. The study also explores the underlying microscopic fracture mechanisms in detail. The results demonstrate that the proposed model effectively captures the influences of hydrides on the ductility of Zr alloys. Specifically, an increase in hydride volume fraction leads to a significant reduction in the ductility and toughness of Zr alloys. The microscopic fracture characteristics of hydrogenated Zr alloys differ significantly between those containing circumferential and radial hydrides, resulting in substantially lower ductility and toughness in samples with radial hydrides under the same conditions. Most importantly, our simulations reveal that misfit strain induced by hydride precipitation is an indispensable factor leading to hydrogen embrittlement in Zr alloys. This research provides valuable insights into the failure mechanisms of hydrogenated Zr alloys and offers a powerful tool for accurately modeling their fracture behavior.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"18 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143576110","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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