Pub Date : 2024-11-22DOI: 10.1016/j.ijplas.2024.104185
Zhipeng Zhang, Yao Tang, Qishan Huang, Haofei Zhou
In the presence of intrinsic lattice distortion and local concentration waves, high-entropy alloys (HEAs) possess unique microstructures, deformation patterns of dislocations and grain boundaries (GBs), and superior mechanical properties. In contrast to traditional crystalline metals, GBs in HEAs have been revealed to exhibit spontaneous roughening behavior, which reduces their migration ability and weakens the plastic deformability of HEAs. In addition, hydrostatic pressure (HP) treatment can modify the microstructure and deformability of GBs in HEAs, leading to enhanced strength and ductility in HEAs. In the present work, we aim to investigate the effect of HP on GB structural evolution in HEAs and reveal the HP-induced enhancement of plastic deformability via molecular dynamics (MD) simulations. Using a FeNiCrCoCu alloy as an example, we have demonstrated that the initially rough GBs in the HEA samples undergo a smoothing mechanism under the application of HP. The GB smoothing mechanism depends not only on the initial GB misorientation and microstructure, but also on the temperature and GB segregation. For the <110>(113) GB, the GB roughness is featured by individual GB segments connected by atomic-scale disconnections. Under HP, the disconnections glide along the GB plane and annihilate with neighboring disconnections, reducing the roughness of the GB. For <110>(112), <110>(114), <110>(116) and <110>(223) GBs, atomic rearrangements take place in local GB segments under HP, resulting in structural adjustment and GB smoothing. These HP-induced GB smoothing mechanisms can increase the plastic deformability of GBs under shear loading. Our findings deepen the understanding of GB plasticity in HEAs and provide insights into GB engineering through HP treatment.
由于存在固有晶格畸变和局部集中波，高熵合金（HEAs）具有独特的微观结构、位错和晶界（GBs）变形模式以及优异的机械性能。与传统的结晶金属相比，HEA 中的 GBs 表现出自发的粗化行为，这降低了它们的迁移能力，削弱了 HEAs 的塑性变形能力。此外，静水压（HP）处理可以改变 HEA 中 GB 的微观结构和变形性，从而提高 HEA 的强度和延展性。在本研究中，我们旨在通过分子动力学（MD）模拟研究 HP 对 HEA 中 GB 结构演变的影响，并揭示 HP 诱导的塑性变形能力增强。以铁镍铬钴铜合金为例，我们证明了在应用 HP 的情况下，HEA 样品中最初粗糙的 GB 会发生平滑机制。碳化硅平滑机制不仅取决于初始碳化硅错向和显微组织，还取决于温度和碳化硅偏析。对于<110>(113) GB，GB粗糙度的特征是由原子尺度断开连接的单个GB段。在高温下，断开物沿着 GB 平面滑行，并与相邻的断开物湮灭，从而降低了 GB 的粗糙度。对于<110>(112)、<110>(114)、<110>(116)和<110>(223) GB，原子重排发生在HP下的局部GB段，导致结构调整和GB平滑。这些由 HP 引起的 GB 平滑机制可以提高 GB 在剪切加载下的塑性变形能力。我们的研究结果加深了对 HEA 中 GB 塑性的理解，并为通过 HP 处理 GB 工程提供了启示。
{"title":"Hydrostatic pressure-mediated grain boundary smoothing and plastic deformability in high-entropy alloys","authors":"Zhipeng Zhang, Yao Tang, Qishan Huang, Haofei Zhou","doi":"10.1016/j.ijplas.2024.104185","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104185","url":null,"abstract":"In the presence of intrinsic lattice distortion and local concentration waves, high-entropy alloys (HEAs) possess unique microstructures, deformation patterns of dislocations and grain boundaries (GBs), and superior mechanical properties. In contrast to traditional crystalline metals, GBs in HEAs have been revealed to exhibit spontaneous roughening behavior, which reduces their migration ability and weakens the plastic deformability of HEAs. In addition, hydrostatic pressure (HP) treatment can modify the microstructure and deformability of GBs in HEAs, leading to enhanced strength and ductility in HEAs. In the present work, we aim to investigate the effect of HP on GB structural evolution in HEAs and reveal the HP-induced enhancement of plastic deformability via molecular dynamics (MD) simulations. Using a FeNiCrCoCu alloy as an example, we have demonstrated that the initially rough GBs in the HEA samples undergo a smoothing mechanism under the application of HP. The GB smoothing mechanism depends not only on the initial GB misorientation and microstructure, but also on the temperature and GB segregation. For the <110>(113) GB, the GB roughness is featured by individual GB segments connected by atomic-scale disconnections. Under HP, the disconnections glide along the GB plane and annihilate with neighboring disconnections, reducing the roughness of the GB. For <110>(112), <110>(114), <110>(116) and <110>(223) GBs, atomic rearrangements take place in local GB segments under HP, resulting in structural adjustment and GB smoothing. These HP-induced GB smoothing mechanisms can increase the plastic deformability of GBs under shear loading. Our findings deepen the understanding of GB plasticity in HEAs and provide insights into GB engineering through HP treatment.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"7 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691044","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}
In ultrahigh-strength maraging steels, nanoprecipitates increase yield strength increments with low work hardening, which is detrimental to their applications. In this study, core–shell nanoprecipitates were introduced to modulate strength, ductility, and work hardening in ultrahigh-strength stainless steel with a tensile strength of 2020 ± 23 MPa and uniform elongation of 9.0% ± 0.9%. The formation of core–shell nanoprecipitates and their effects on the work hardening of steel were systematically investigated. Evidently, a Ni3Ti core was encapsulated by a Mn-enriched shell with an ordered structure, which is coherent with the martensitic matrix. During deformation, the ordered Mn-enriched shells were disrupted by dislocation cutting, leading to an increase in structure distortion in the vicinity of the Ni3Ti cores. This promoted the multiplication of dislocations, thereby substantially improving work hardening and uniform elongation. The yield strength was primarily contributed by multiple nanoprecipitates, including the core–shell, α′-Cr, and Mo-rich precipitates.
{"title":"Formation of core-shell nanoprecipitates and their effects on work hardening in an ultrahigh-strength stainless steel","authors":"Junpeng Li, Weiguo Jiang, Yang Zhang, Liyuan Liu, Yongzheng Yu, Junhua Luan, Zengbao Jiao, Chain Tsuan Liu, Zhongwu Zhang","doi":"10.1016/j.ijplas.2024.104184","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104184","url":null,"abstract":"In ultrahigh-strength maraging steels, nanoprecipitates increase yield strength increments with low work hardening, which is detrimental to their applications. In this study, core–shell nanoprecipitates were introduced to modulate strength, ductility, and work hardening in ultrahigh-strength stainless steel with a tensile strength of 2020 ± 23 MPa and uniform elongation of 9.0% ± 0.9%. The formation of core–shell nanoprecipitates and their effects on the work hardening of steel were systematically investigated. Evidently, a Ni<sub>3</sub>Ti core was encapsulated by a Mn-enriched shell with an ordered structure, which is coherent with the martensitic matrix. During deformation, the ordered Mn-enriched shells were disrupted by dislocation cutting, leading to an increase in structure distortion in the vicinity of the Ni<sub>3</sub>Ti cores. This promoted the multiplication of dislocations, thereby substantially improving work hardening and uniform elongation. The yield strength was primarily contributed by multiple nanoprecipitates, including the core–shell, α′-Cr, and Mo-rich precipitates.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"5 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690609","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 : 2024-11-22DOI: 10.1016/j.ijplas.2024.104179
Benoit Jordan, Dirk Mohr
Research on data-driven constitutive models has demonstrated their outstanding ability to provide highly accurate predictions of the general stress-strain response after learning from data only. Here, we demonstrate that physics-based models can equally benefit from training procedures relying on big data. Specifically, we employ the thermo-mechanically coupled viscoplasticity model [Anand, L., Ames, N.M., Srivastava, V., Chester, S., 2009. A thermo-mechanically coupled theory for large deformations of amorphous polymers. Part 1: Formulation. International Journal of Plasticity] to describe the large deformation response of polypropylene. It combines both mechanism-based evolution equations and high mathematical flexibility. More than 100 constant velocity and strain rate jump experiments are performed on flat tensile specimens extracted from 3mm thick isotactic polypropylene sheets. The exact cross-sectional area is measured with surround DIC, while an IR camera monitored the surface temperature field. The experiments typically reached true strains greater than 0.8 and cover temperatures and strain rates ranging from 25 to 85°C and 10-4 to 100 s-1, respectively. Training over 100’000 unique random combinations of experiments is performed to identify all model parameters. The effect of the training (and testing) subsets size and composition is carefully analyzed to ensure a high generalization ability. It is found that training based on 26 randomly-selected experiments leads to the most robust parameter estimates. The obtained model performs remarkably well on all our experiments (among which 70% are unseen during training) with a root mean square error of less than 1.5 MPa. As a byproduct, we also found that there exists a subset of two specific experiments for training that lead to an equally accurate model for polypropylene.
{"title":"Training of a Physics-based Thermo-Viscoplasticity Model on Big Data for Polypropylene","authors":"Benoit Jordan, Dirk Mohr","doi":"10.1016/j.ijplas.2024.104179","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104179","url":null,"abstract":"Research on data-driven constitutive models has demonstrated their outstanding ability to provide highly accurate predictions of the general stress-strain response after learning from data only. Here, we demonstrate that physics-based models can equally benefit from training procedures relying on big data. Specifically, we employ the thermo-mechanically coupled viscoplasticity model [Anand, L., Ames, N.M., Srivastava, V., Chester, S., 2009. A thermo-mechanically coupled theory for large deformations of amorphous polymers. Part 1: Formulation. International Journal of Plasticity] to describe the large deformation response of polypropylene. It combines both mechanism-based evolution equations and high mathematical flexibility. More than 100 constant velocity and strain rate jump experiments are performed on flat tensile specimens extracted from 3mm thick isotactic polypropylene sheets. The exact cross-sectional area is measured with surround DIC, while an IR camera monitored the surface temperature field. The experiments typically reached true strains greater than 0.8 and cover temperatures and strain rates ranging from 25 to 85°C and 10<sup>-4</sup> to 10<sup>0</sup> s<sup>-1</sup>, respectively. Training over 100’000 unique random combinations of experiments is performed to identify all model parameters. The effect of the training (and testing) subsets size and composition is carefully analyzed to ensure a high generalization ability. It is found that training based on 26 randomly-selected experiments leads to the most robust parameter estimates. The obtained model performs remarkably well on all our experiments (among which 70% are unseen during training) with a root mean square error of less than 1.5 MPa. As a byproduct, we also found that there exists a subset of two specific experiments for training that lead to an equally accurate model for polypropylene.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"15 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691046","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 : 2024-11-20DOI: 10.1016/j.ijplas.2024.104181
Yuejie Hu, Chuanjie Wang, Haiyang Wang, Gang Chen, Xingrong Chu, Guannan Chu, Han Wang, Shihao Wu
Void characteristics are fundamentally correlated with the macroscopic deformation responses of materials, yet traditional modeling methods exhibit inherent limitations in data mining. In this study, a machine learning (ML) framework is proposed to predict the full-field strain evolution of Cu/Ni clad foils, and the impact of intrinsic voids is quantitatively assessed using interpretative analysis methods. The local strain and void data are extracted and integrated through digital image correlation and computed tomography. To accommodate the nature of the constructed dataset, a ML model is established with reference to the concept of time series forecasting. Subsequently, the influence of microstructural features such as volume fraction (VVF), area, and size of voids are investigated, alongside their role in driving local strain evolution. This approach successfully predicts strain localization, and accurately pinpoints the onset of plastic instability and the location of crack initiation. The VVF is identified as the most predominant factor, followed by void size along the tensile direction and grain size. The strongest association is observed between the VVF and grain size, which intensifies over extended time scales. Moreover, as void coalescence is almost completed, the promoting effect of the concentrated void distribution on macroscopic strain concentration will become increasingly pronounced. These findings provide novel perspectives for exploring the intricate relationship between deformation and damage.
{"title":"Investigation of full-field strain evolution behavior of Cu/Ni clad foils by interpretable machine learning","authors":"Yuejie Hu, Chuanjie Wang, Haiyang Wang, Gang Chen, Xingrong Chu, Guannan Chu, Han Wang, Shihao Wu","doi":"10.1016/j.ijplas.2024.104181","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104181","url":null,"abstract":"Void characteristics are fundamentally correlated with the macroscopic deformation responses of materials, yet traditional modeling methods exhibit inherent limitations in data mining. In this study, a machine learning (ML) framework is proposed to predict the full-field strain evolution of Cu/Ni clad foils, and the impact of intrinsic voids is quantitatively assessed using interpretative analysis methods. The local strain and void data are extracted and integrated through digital image correlation and computed tomography. To accommodate the nature of the constructed dataset, a ML model is established with reference to the concept of time series forecasting. Subsequently, the influence of microstructural features such as volume fraction (VVF), area, and size of voids are investigated, alongside their role in driving local strain evolution. This approach successfully predicts strain localization, and accurately pinpoints the onset of plastic instability and the location of crack initiation. The VVF is identified as the most predominant factor, followed by void size along the tensile direction and grain size. The strongest association is observed between the VVF and grain size, which intensifies over extended time scales. Moreover, as void coalescence is almost completed, the promoting effect of the concentrated void distribution on macroscopic strain concentration will become increasingly pronounced. These findings provide novel perspectives for exploring the intricate relationship between deformation and damage.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"22 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673435","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 : 2024-11-15DOI: 10.1016/j.ijplas.2024.104159
K. Nalepka, J. Tabin, J. Kawałko, A. Brodecki, P. Bała, Z. Kowalewski
AISI 304 steel experiences plastic flow instability during tension at room temperature if appropriate conditions are applied: a low strain rate and a sufficiently long gauge section of the sample. Then, propagation of the strain-localised band is activated. The electron backscattered diffraction (EBSD) research revealed that the reason is not only the difference in the content of the secondary phase – martensite α’ across the front face, but also the change in the volume fraction of austenite grains with Copper (Cu) and Goss-Brass (GB) orientation. Consequently, there is a division between two areas of high and limited deformation capacity. The tendency to maintain the continuity of deformation fields induces a massive rotation of austenite grains to Cu and GB orientations, which then undergo shearing and phase transformation. As a result, momentary strain accumulation leaves behind a stiffer zone. It is shown that the trapping of austenite grains prone to large deformations, inside the matrix with Cu and GB orientations, makes the formation of a plastic strain front possible. These features improve the ductility and strength of the 304 steel over 316L and 316LN at room temperature. The in-situ EBSD tension studies for the considered grades reveal three developing textures, with their comparison showing a gradual decrease in the preferences of the Cu and GB components. Thus, the appearing bands of the accumulated strains in 316L are limited by the Cu and GB areas, while such blockages do not occur in 316LN. The presented strengthening mechanism is confirmed by the digital image correlation (DIC) measurements. The root-mean-square (RMS) function of strains along the tensile direction, characterising the linear surroundings of the considered point, is introduced as a tool for linking the micro and macro scales. The experimental results provide a basis for explaining discontinuous front propagation at a temperature near 0 K.
在室温条件下，AISI 304 钢在拉伸过程中会出现塑性流动不稳定性，如果采用适当的条件：低应变率和足够长的试样截面。然后，应变定位带的传播被激活。电子反向散射衍射 (EBSD) 研究表明，原因不仅在于整个正面的次生相--马氏体 α' 的含量不同，还在于铜 (Cu) 和戈斯-布拉斯 (GB) 取向奥氏体晶粒体积分数的变化。因此，变形能力分为高变形能力和有限变形能力两个区域。保持变形场连续性的趋势导致奥氏体晶粒向 Cu 和 GB 方向发生大量旋转，然后发生剪切和相变。因此，瞬时应变积累会留下一个较硬的区域。研究表明，在具有 Cu 和 GB 取向的基体内部，容易发生大变形的奥氏体晶粒的捕获使塑性应变前沿的形成成为可能。与 316L 和 316LN 相比，这些特点提高了 304 钢在室温下的延展性和强度。对所考虑的钢种进行的原位 EBSD 拉伸研究揭示了三种发展中的纹理，其比较显示出铜和 GB 成分的偏好逐渐降低。因此，在 316L 中出现的累积应变带受到了铜和 GB 区域的限制，而在 316LN 中则没有出现这种阻塞。数字图像相关（DIC）测量结果证实了上述强化机制。拉伸方向应变的均方根（RMS）函数描述了所考虑点的线性周围环境，被引入作为连接微观和宏观尺度的工具。实验结果为解释温度接近 0 K 时的不连续前沿传播提供了依据。
{"title":"Plastic Flow Instability in Austenitic Stainless Steels at Room Temperature: Macroscopic Tests and Microstructural Analysis","authors":"K. Nalepka, J. Tabin, J. Kawałko, A. Brodecki, P. Bała, Z. Kowalewski","doi":"10.1016/j.ijplas.2024.104159","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104159","url":null,"abstract":"AISI 304 steel experiences plastic flow instability during tension at room temperature if appropriate conditions are applied: a low strain rate and a sufficiently long gauge section of the sample. Then, propagation of the strain-localised band is activated. The electron backscattered diffraction (EBSD) research revealed that the reason is not only the difference in the content of the secondary phase – martensite α’ across the front face, but also the change in the volume fraction of austenite grains with Copper (Cu) and Goss-Brass (GB) orientation. Consequently, there is a division between two areas of high and limited deformation capacity. The tendency to maintain the continuity of deformation fields induces a massive rotation of austenite grains to Cu and GB orientations, which then undergo shearing and phase transformation. As a result, momentary strain accumulation leaves behind a stiffer zone. It is shown that the trapping of austenite grains prone to large deformations, inside the matrix with Cu and GB orientations, makes the formation of a plastic strain front possible. These features improve the ductility and strength of the 304 steel over 316L and 316LN at room temperature. The in-situ EBSD tension studies for the considered grades reveal three developing textures, with their comparison showing a gradual decrease in the preferences of the Cu and GB components. Thus, the appearing bands of the accumulated strains in 316L are limited by the Cu and GB areas, while such blockages do not occur in 316LN. The presented strengthening mechanism is confirmed by the digital image correlation (DIC) measurements. The root-mean-square (RMS) function of strains along the tensile direction, characterising the linear surroundings of the considered point, is introduced as a tool for linking the micro and macro scales. The experimental results provide a basis for explaining discontinuous front propagation at a temperature near 0 K.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"1 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642745","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 : 2024-11-13DOI: 10.1016/j.ijplas.2024.104180
Junyang He, Weijin Cai, Na Li, Li Wang, Zhangwei Wang, Shuai Dai, Zhifeng Lei, Zhenggang Wu, Min Song, Zhaoping Lu
Precipitation engineering is one of the most effective means to enhance the strength of an alloy, which essentially requires precipitates with certain deformability, fine size, and uniform distribution. However, for multicomponent alloy systems, the chemical complexity poses significant difficulties in applying this strengthening method due to the diversity and brittleness of the potential precipitate phases. In this work, we demonstrated the precipitation engineering in a chemically complex prototype alloy NiCoV. Specifically, formation of detrimental σ, μ and Heusler phases was avoided by reducing the V content, and a two-step short-term annealing was designed to trigger homogeneous κ nucleation while inhibiting its rapid coarsening. It is found that both grain and phase boundaries can trap V atoms, which not only pins these interfaces but also hinders the V partitioning needed for κ growth. Consequently, we achieved an ultrafine κ/γ architecture in the NiCoV0.9 alloy, which surprisingly exhibited an ultrahigh yield strength of 1.6 GPa and a total work-hardening amount of 219 MPa. Our analysis indicates that the hetero-deformation induced (HDI) stress is mainly responsible for the high strength, while the coherent nature of phase boundaries and decent deformability of κ alleviate stress concentration, giving rise to the pronounced work-hardening. Our work highlights the importance of suitable phase selection and delicate substructure tailoring in precipitation engineering, with key findings also useful for enhancing overall mechanical properties in other multicomponent alloys.
析出工程是提高合金强度的最有效手段之一，它主要要求析出物具有一定的变形能力、细小尺寸和均匀分布。然而，对于多组分合金体系来说，由于潜在析出相的多样性和脆性，化学复杂性给应用这种强化方法带来了很大困难。在这项工作中，我们展示了化学性质复杂的原型合金 NiCoV 的沉淀工程。具体来说，通过降低 V 含量避免了有害的 σ、μ 和 Heusler 相的形成，并设计了两步短期退火来引发均匀的 κ 成核，同时抑制其快速粗化。研究发现，晶界和相界都会捕获 V 原子，这不仅会对这些界面造成销蚀，还会阻碍κ生长所需的 V 分配。因此，我们在 NiCoV0.9 合金中实现了超精细的 κ/γ 结构，并出人意料地表现出 1.6 GPa 的超高屈服强度和 219 MPa 的总加工硬化量。我们的分析表明，异质变形诱导应力（HDI）是产生高强度的主要原因，而相界的一致性和 κ 的良好变形性缓解了应力集中，从而产生了明显的加工硬化。我们的研究工作强调了在沉淀工程中选择合适的相和定制精细的子结构的重要性，其主要发现也有助于提高其他多组分合金的整体机械性能。
{"title":"Significantly enhanced mechanical properties of NiCoV medium-entropy alloy via precipitation engineering","authors":"Junyang He, Weijin Cai, Na Li, Li Wang, Zhangwei Wang, Shuai Dai, Zhifeng Lei, Zhenggang Wu, Min Song, Zhaoping Lu","doi":"10.1016/j.ijplas.2024.104180","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104180","url":null,"abstract":"Precipitation engineering is one of the most effective means to enhance the strength of an alloy, which essentially requires precipitates with certain deformability, fine size, and uniform distribution. However, for multicomponent alloy systems, the chemical complexity poses significant difficulties in applying this strengthening method due to the diversity and brittleness of the potential precipitate phases. In this work, we demonstrated the precipitation engineering in a chemically complex prototype alloy NiCoV. Specifically, formation of detrimental σ, μ and Heusler phases was avoided by reducing the V content, and a two-step short-term annealing was designed to trigger homogeneous κ nucleation while inhibiting its rapid coarsening. It is found that both grain and phase boundaries can trap V atoms, which not only pins these interfaces but also hinders the V partitioning needed for κ growth. Consequently, we achieved an ultrafine κ/γ architecture in the NiCoV<sub>0.9</sub> alloy, which surprisingly exhibited an ultrahigh yield strength of 1.6 GPa and a total work-hardening amount of 219 MPa. Our analysis indicates that the hetero-deformation induced (HDI) stress is mainly responsible for the high strength, while the coherent nature of phase boundaries and decent deformability of κ alleviate stress concentration, giving rise to the pronounced work-hardening. Our work highlights the importance of suitable phase selection and delicate substructure tailoring in precipitation engineering, with key findings also useful for enhancing overall mechanical properties in other multicomponent alloys.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"72 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601175","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 : 2024-11-12DOI: 10.1016/j.ijplas.2024.104178
Yufeng Song , Qin Zhang , Heng Li , Xudong Yuan , Yuqiang Chen , Dingding Lu , Wenhui Liu
Al-Cu-Mg alloys, as the most widely used lightweight structural materials, have been recognized as promising candidates in the transportation field for a low-carbon economy. However, the tensile strength and plasticity of alloys cannot be simultaneously improved to satisfy the requirements of continuously upgraded transportation vehicles. In this work, inspired by high-tensile strength and high plasticity of cobweb structure, a novel cobweb-like sub-grain structure was developed in Al-Cu-Mg alloys by a successive solution, high-strain-rate rolling (4.4 s-1), cryogenic treatment (–196 °C) and aging process (SRCA). Notably, the tensile strength and plasticity of this alloy were superior to those reported in the current study. An ultrahigh Vickers hardness and tensile strength value of 206.2 Hv and 619.6 MPa, which were 39.8 % and 31.8 % higher than those of traditional T6 heat-treated Al-Cu-Mg alloys, were obtained after SRCA. Meanwhile, an increase in the elongation of this alloy from 4.31 % to 8.23 % (increase of 90.9 %) was also achieved. More importantly, the high strength-plasticity (“double high”) Al-Cu-Mg alloy was attributed to a cobweb-like sub-grain structure, which was proposed for the first time by utilizing reverse thinking to enhance plasticity through elevating dislocations, due to the formation of high-density dislocations from high-strain-rate rolling and rearrangement effect of dislocations from cryogenic treatment. Furthermore, the strength-plasticity mechanism was verified using in-situ tensile electron back scatter diffraction (EBSD), molecular dynamics (MD) simulations, and crystal plasticity (CP) models. The results indicated that the cobweb-like sub-grain structure, resembling countless walls, formed barriers that hindered dislocation migration towards high-angle grain boundaries (HAGBs) and absorbed them, thereby reducing the occurrence of stress concentration zones, i.e., the dislocation absorption and stress-strain sharing mechanisms. Additionally, the strengthening mechanism was associated with synergistic strengthening by multiscale microstructures, including micron-sized grains, micron-sized high-density dislocation lattices, and nanosized Al2CuMg phases, which were activated by successive deformation processes. Consequently, the concept of biomimetic structure design, which may serve as an effective method for achieving structural materials with high strength-plasticity synergy, can be extended to transportation fields, such as railway tracks and body structure design.
{"title":"A novel cobweb-like sub-grain structured Al-Cu-Mg alloy with high strength-plasticity synergy","authors":"Yufeng Song , Qin Zhang , Heng Li , Xudong Yuan , Yuqiang Chen , Dingding Lu , Wenhui Liu","doi":"10.1016/j.ijplas.2024.104178","DOIUrl":"10.1016/j.ijplas.2024.104178","url":null,"abstract":"<div><div>Al-Cu-Mg alloys, as the most widely used lightweight structural materials, have been recognized as promising candidates in the transportation field for a low-carbon economy. However, the tensile strength and plasticity of alloys cannot be simultaneously improved to satisfy the requirements of continuously upgraded transportation vehicles. In this work, inspired by high-tensile strength and high plasticity of cobweb structure, a novel cobweb-like sub-grain structure was developed in Al-Cu-Mg alloys by a successive solution, high-strain-rate rolling (4.4 s<sup>-1</sup>), cryogenic treatment (–196 °C) and aging process (SRCA). Notably, the tensile strength and plasticity of this alloy were superior to those reported in the current study. An ultrahigh Vickers hardness and tensile strength value of 206.2 Hv and 619.6 MPa, which were 39.8 % and 31.8 % higher than those of traditional T6 heat-treated Al-Cu-Mg alloys, were obtained after SRCA. Meanwhile, an increase in the elongation of this alloy from 4.31 % to 8.23 % (increase of 90.9 %) was also achieved. More importantly, the high strength-plasticity (“double high”) Al-Cu-Mg alloy was attributed to a cobweb-like sub-grain structure, which was proposed for the first time by utilizing reverse thinking to enhance plasticity through elevating dislocations, due to the formation of high-density dislocations from high-strain-rate rolling and rearrangement effect of dislocations from cryogenic treatment. Furthermore, the strength-plasticity mechanism was verified using <em>in-situ</em> tensile electron back scatter diffraction (EBSD), molecular dynamics (MD) simulations, and crystal plasticity (CP) models. The results indicated that the cobweb-like sub-grain structure, resembling countless walls, formed barriers that hindered dislocation migration towards high-angle grain boundaries (HAGBs) and absorbed them, thereby reducing the occurrence of stress concentration zones, i.e., the dislocation absorption and stress-strain sharing mechanisms. Additionally, the strengthening mechanism was associated with synergistic strengthening by multiscale microstructures, including micron-sized grains, micron-sized high-density dislocation lattices, and nanosized Al<sub>2</sub>CuMg phases, which were activated by successive deformation processes. Consequently, the concept of biomimetic structure design, which may serve as an effective method for achieving structural materials with high strength-plasticity synergy, can be extended to transportation fields, such as railway tracks and body structure design.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"184 ","pages":"Article 104178"},"PeriodicalIF":9.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599838","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 : 2024-11-10DOI: 10.1016/j.ijplas.2024.104177
Changqiu Ji, Yang Li, Zhipeng Sun, Aiya Cui, Yong Xin, Yinan Cui
A systematic multiscale-informed model is developed to predict the irradiation growth behavior of Zr-Sn-Nb alloys, which considers the anisotropy and temperature dependence of both plasticity and irradiation, as well as the alloying effect of Zr alloys. This model consists of a cluster dynamics submodel to consider the kinetics of irradiation defect, an alloying effect submodel informed by atomic simulations and experiments, a microstructure transition submodel derived from discrete dislocation dynamics, and a continuous irradiation growth submodel based on crystal plasticity. It effectively captures the irradiation-induced coevolution of multiple microstructures, including point defects, mobile clusters, dislocation lines and irradiation loops on the prismatic and basal plane, as well as Nb-induced precipitates. It is suitable for high-dose irradiation conditions as it reasonably considers the transition from high-density irradiation loops to tangled dislocation network. The predicted irradiation growth strain, as well as the density and size of irradiation loops, are in good agreement with almost all the available experiments for pure Zr, Zr-Sn, Zr- Nb, and Zr-Sn-Nb alloys at different irradiation doses in the temperature range of 473 - 673 K. This work is hoped to provide a powerful tool for developing irradiation resistance cladding materials.
该模型考虑了塑性和辐照的各向异性和温度依赖性，以及锆合金的合金效应。该模型包括一个考虑辐照缺陷动力学的团簇动力学子模型、一个基于原子模拟和实验的合金效应子模型、一个从离散位错动力学推导出的微结构转变子模型，以及一个基于晶体塑性的连续辐照生长子模型。它有效地捕捉了辐照诱导的多种微观结构的共同演化，包括点缺陷、移动簇、位错线和棱柱面和基面上的辐照环，以及铌诱导析出物。它合理地考虑了从高密度辐照环到纠结位错网络的过渡，因此适用于高剂量辐照条件。所预测的辐照生长应变以及辐照环的密度和尺寸与几乎所有现有的实验结果都非常吻合，这些实验是在温度为 473 - 673 K 的范围内，对纯 Zr、Zr-Sn、Zr-Nb 和 Zr-Sn-Nb 合金进行不同剂量的辐照。
{"title":"Multiscale-informed irradiation growth model of Zr-Sn-Nb alloys","authors":"Changqiu Ji, Yang Li, Zhipeng Sun, Aiya Cui, Yong Xin, Yinan Cui","doi":"10.1016/j.ijplas.2024.104177","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104177","url":null,"abstract":"A systematic multiscale-informed model is developed to predict the irradiation growth behavior of Zr-Sn-Nb alloys, which considers the anisotropy and temperature dependence of both plasticity and irradiation, as well as the alloying effect of Zr alloys. This model consists of a cluster dynamics submodel to consider the kinetics of irradiation defect, an alloying effect submodel informed by atomic simulations and experiments, a microstructure transition submodel derived from discrete dislocation dynamics, and a continuous irradiation growth submodel based on crystal plasticity. It effectively captures the irradiation-induced coevolution of multiple microstructures, including point defects, mobile clusters, dislocation lines and irradiation loops on the prismatic and basal plane, as well as Nb-induced precipitates. It is suitable for high-dose irradiation conditions as it reasonably considers the transition from high-density irradiation loops to tangled dislocation network. The predicted irradiation growth strain, as well as the density and size of irradiation loops, are in good agreement with almost all the available experiments for pure Zr, Zr-Sn, Zr- Nb, and Zr-Sn-Nb alloys at different irradiation doses in the temperature range of 473 - 673 K. This work is hoped to provide a powerful tool for developing irradiation resistance cladding materials.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"35 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597004","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 : 2024-11-10DOI: 10.1016/j.ijplas.2024.104167
Chunfeng Du, Yipeng Gao, Min Zha, Cheng Wang, Jian Wang, Hui-Yuan Wang
Superplastic deformation in metals and alloys, characterized by ultrahigh ductility (exceeding 300%) without cracking at elevated temperatures, is a critical process for manufacturing complex-shaped components. While a few grain-boundary (GB)-mediated deformation mechanisms have been identified as essential contributors to superplasticity in fine-grained polycrystals (grain size is typically less than 10 μm), it is still a challenge to maintain a steady fine-grained microstructure and sustainable plastic flow at high temperatures. Partially due to the lack of a quantitative description of dislocation-GB reactions, it has not been well recognized how grain coarsening can be suppressed by the external loading during superplastic deformation. In this work, we address this challenge by formulating a disclination-dislocation coupling equation within the Lie-algebra framework, providing a quantitative understanding of the interactions between disclinations, dislocations, and GBs. Using quasi-in-situ electron backscattered diffraction (EBSD) analysis in Mg alloys, we systematically investigate the multiscale interactions of the defects and their impact on grain structure evolution. Three key mechanisms that suppress conventional grain coarsening have been identified, i.e., disclination-assisted GB accommodation, disclination-GB pinning, and disclination-induced sub-GB crossing, all of which are captured by the proposed equation. This study contributes to the broader field of plasticity by linking macroscopic deformation behavior with microscopic mechanisms, offering new insights into the theory of superplastic deformation in metals and alloys.
{"title":"The evolution of grain boundary structure mediated by disclinations in magnesium alloys under superplastic deformation","authors":"Chunfeng Du, Yipeng Gao, Min Zha, Cheng Wang, Jian Wang, Hui-Yuan Wang","doi":"10.1016/j.ijplas.2024.104167","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104167","url":null,"abstract":"Superplastic deformation in metals and alloys, characterized by ultrahigh ductility (exceeding 300%) without cracking at elevated temperatures, is a critical process for manufacturing complex-shaped components. While a few grain-boundary (GB)-mediated deformation mechanisms have been identified as essential contributors to superplasticity in fine-grained polycrystals (grain size is typically less than 10 μm), it is still a challenge to maintain a steady fine-grained microstructure and sustainable plastic flow at high temperatures. Partially due to the lack of a quantitative description of dislocation-GB reactions, it has not been well recognized how grain coarsening can be suppressed by the external loading during superplastic deformation. In this work, we address this challenge by formulating a disclination-dislocation coupling equation within the Lie-algebra framework, providing a quantitative understanding of the interactions between disclinations, dislocations, and GBs. Using <em>quasi-in-situ</em> electron backscattered diffraction (EBSD) analysis in Mg alloys, we systematically investigate the multiscale interactions of the defects and their impact on grain structure evolution. Three key mechanisms that suppress conventional grain coarsening have been identified, i.e., disclination-assisted GB accommodation, disclination-GB pinning, and disclination-induced sub-GB crossing, all of which are captured by the proposed equation. This study contributes to the broader field of plasticity by linking macroscopic deformation behavior with microscopic mechanisms, offering new insights into the theory of superplastic deformation in metals and alloys.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"15 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597168","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 : 2024-11-09DOI: 10.1016/j.ijplas.2024.104176
Fuhua Cao , Hongyi Li , Yan Chen , Haiying Wang , Zheng Peng , Lan-Hong Dai
Refractory high entropy superalloys (RHESs), known for their excellent high temperature performance, exhibit promising characteristics but are challenged by significant brittleness. Efforts to enhance plasticity through microstructure regulation have achieved only limited success, largely due to the unclear underlying fracture mechanisms of the superstructure. In this study, we systematically investigate the fracture mechanisms of the AlMo0.5NbTa0.5TiZr RHES from microscopic to electronic scales. Interestingly, both experimental and simulation results reveal that the ordered B2 phase demonstrates non-negligible plastic deformation capabilities during fracture, including deformation twinning and amorphization. Despite this, the fracture resistance of the B2 phase is lower compared to the A2/B2 interface and disordered A2 phase, even though the A2 phase shows less twinning and amorphization. Ab initio molecular dynamics simulations, combined with electronic behavior analysis, indicate that bonds involving Al and Zr in the B2 phase often exist in an anti-bonding state, making them more prone to breaking under load. This study provides deeper insights into the fracture mechanisms of the A2/B2 superstructure and its constituent phases at both atomic and electronic levels, offering a systematic approach to improving the fracture properties of such RHESs.
{"title":"Atomic mechanisms for the fracture of AlMo0.5NbTa0.5TiZr refractory high entropy superalloy","authors":"Fuhua Cao , Hongyi Li , Yan Chen , Haiying Wang , Zheng Peng , Lan-Hong Dai","doi":"10.1016/j.ijplas.2024.104176","DOIUrl":"10.1016/j.ijplas.2024.104176","url":null,"abstract":"<div><div>Refractory high entropy superalloys (RHESs), known for their excellent high temperature performance, exhibit promising characteristics but are challenged by significant brittleness. Efforts to enhance plasticity through microstructure regulation have achieved only limited success, largely due to the unclear underlying fracture mechanisms of the superstructure. In this study, we systematically investigate the fracture mechanisms of the AlMo<sub>0.5</sub>NbTa<sub>0.5</sub>TiZr RHES from microscopic to electronic scales. Interestingly, both experimental and simulation results reveal that the ordered B2 phase demonstrates non-negligible plastic deformation capabilities during fracture, including deformation twinning and amorphization. Despite this, the fracture resistance of the B2 phase is lower compared to the A2/B2 interface and disordered A2 phase, even though the A2 phase shows less twinning and amorphization. Ab initio molecular dynamics simulations, combined with electronic behavior analysis, indicate that bonds involving Al and Zr in the B2 phase often exist in an anti-bonding state, making them more prone to breaking under load. This study provides deeper insights into the fracture mechanisms of the A2/B2 superstructure and its constituent phases at both atomic and electronic levels, offering a systematic approach to improving the fracture properties of such RHESs.</div></div>","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"183 ","pages":"Article 104176"},"PeriodicalIF":9.4,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597041","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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