1-20. Effects of multiaxial strain on the morphology and kinetics evolution of nanoscale phase

Yongsheng Li1,2,*, Xinwen Tong1,2, Zhengwei Yan1,2, Dong Wang1,2, Shujing Shi1,2

1.School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China 2. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, Nanjing 210094, China

Abstract:A high-throughput simulation was performed to study the multistrain on the morphology and kinetics evolution of nanoscale precipitates. The changes of morphology and precipitation rate are clarified for uniaxial, biaxial and triaxial strain by utilizing the three-dimensional phase-field simulation, combining the free energy and shape change of precipitates. For the anisotropic elasticity, there is no obvious difference in precipitation kinetics under uniaxial strain. Biaxial strain promotes precipitation compared with stress-free state, and the combined tensile and compressive biaxial strain results in the fast precipitation in biaxial strain states. As for the triaxial strain, the most dramatical acceleration on precipitation and kinetics derives from biaxial tensile with uniaxial compressive strain, while the slowest precipitation is under the triaxial compressive strain. In addition, the strip-like structure is intensified under mixed triaxial strain, especially for the biaxial tensile with uniaxial compressive strain. Triaxial tensile and compressive strains do not change the shape of precipitates, while the particle size is reduced under triaxial compressive strain. The shape change of precipitates is explained by the relationship of strain distribution and elements migration.

Keywords: Precipitates; Multiaxial strain; Morphology; Kinetics; High-throughput simulation 

多向应变对纳米析出相组织和动力学演化的影响

李永胜 1,2*，童鑫雯 1,2，严正伟 1,2，王栋 1,2，史淑静 1,2

1.南京理工大学，材料科学与工程学院，南京，210094

2.先进金属与金属间化合物材料技术工信部重点实验室，南京，210094

摘要:应力状态对合金相变过程和沉淀相的微观组织演化有重要影响，因此影响材料的力学性能。采用高通量模拟方法研究了多应变状态对纳米颗粒形貌和动力学演化的影响，通过三维相场模拟，结合系统自由能和微观组织取向，阐明了单轴向、两轴向和三轴向应变下析出相微观形貌和沉淀速率的变化规律。各向异性弹性应变对单轴应变下的沉淀动力学没有明显影响。双轴向应变加快了沉淀速率，在拉伸和压缩双轴向应变共同作用下，沉淀速度较快。三轴应变对沉淀和动力学影响最显著的是单轴压缩和双轴拉伸应变组合状态，而三轴压缩应变使得沉淀速率最慢。此外，条带状结构在混合三轴应变作用下得到强化，特别是在双轴拉伸和单轴压缩应
变作用下。三轴拉伸应变和三轴压缩应变都不改变沉淀相的形貌，而三轴压缩应变会使颗粒尺寸减小，三轴向拉应变使得析出相颗粒增大。应变能分布与元素迁移的关系解释了析出相的形态演变。

关键词:多向应变;沉淀相;微观组织;动力学;高通量模拟