Interaction Between Nano-Voids and Migrating Grain Boundary by Molecular Dynamics Simulation
Interaction Between Nano-Voids and Migrating Grain Boundary by Molecular Dynamics Simulation
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DOI：
10.1016/j.actamat.2019.05.020
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发表时间：
2019-04
期刊：
影响因子：
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通讯作者：
Liang Zhang;Y. Shibuta;Cheng Lu;Xiaoxu Huang
中科院分区：
文献类型：
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作者：
Liang Zhang;Y. Shibuta;Cheng Lu;Xiaoxu Huang
了解空洞与晶界之间的相互作用对于利用晶界工程进行抗辐射材料的设计和实现高质量的冶金扩散连接具有重要意义。在本研究中，我们用分子动力学方法系统地研究了纳米空穴与晶格之间的相互作用。整个工作过程中使用了双晶铜样品，并通过剪切变形下的GB迁移实现了GB-孔洞的动态相互作用。研究了大角度金字塔(Σ5(310)GB，Σ5(210)GB)和小角度金字塔(Σ37(750)GB，Σ61(650)GB)，并考察了孔洞尺寸和温度对模拟结果的影响。在低温(T = 10 K)空洞与大角度晶界相互作用过程中，观察到了形变机制从晶格迁移到位错扩展的转变。在较高温度下(T = 300和600 K)，在相互作用过程中，迁移的GB可以被钉扎在空穴、自由穿越的空穴或溶解的空穴上。基于类齐纳方程分析了气泡阻力对气泡运动的影响，结果表明气泡对气泡运动的阻挡作用与气泡的表面积、气泡与气泡的接触程度以及气泡的能量密切相关。通过研究静止晶界处空穴的热稳定性，发现在运动晶界处空穴的溶解不能完全归因于热扩散机制。大角度晶界的动态迁移可以显著加快空穴的溶解时间。原子学分析表明，迁移中的晶格通过结构单元的集体运动重新排列空位表面的原子，晶格的结构相变为空位的迁移提供了有效的扩散通道。与大角度GB相比，小角度GB溶解空穴的能力降低，这可以归因于其较低的GB能量和扩散系数、较快的GB迁移速度以及离散的GB结构。
Understanding the interaction between void and grain boundary (GB) is important to the design of radiation resistant materials by GB engineering and to achieve high quality metallurgical diffusion joining. In this study, the interaction between nano-voids and GBs has been systematically investigated by molecular dynamics simulations. The bicrystal Cu sample was used throughout the work, and the dynamic GB-void interaction was achieved by GB migration under shear deformation. Both high-angle GBs (Σ5 (310) GB, Σ5 (210) GB) and low-angle GBs (Σ37 (750) GB, Σ61 (650) GB) were investigated, and the effect of void size and temperature on the simulation result was examined. The transition of the deformation mechanism from GB migration to dislocation propagation was observed during the interaction between voids and high-angle GBs at low temperature (T = 10 K). At higher temperature (T = 300 and 600 K), the migrating GB can be pinned to voids, freely traversed voids, or dissolved voids in the process of their interaction. The void-drag effect on GB motion was analyzed based on the Zener-like equation, which indicates that the retarding pressure applied to the migrating GB by a void is closely related to the surface area of the void, the degree of contact between GB and void, and GB energy. By investigating the thermal stability of a void at the stationary GB, it was found that the dissolution of voids at a moving GB cannot be attributed solely to the thermal diffusion mechanism. The dynamic migration of high-angle GBs can significantly accelerate the dissolution time of the void. Atomistic analysis indicated that the migrating GB rearranged the atoms on the void surface by the collective motion of structural units, and the GB structural phase transformation provided an efficient diffusion channel for transporting the vacancies. The low-angle GBs show a reduced ability to dissolve the voids than the high-angle GBs, which can be ascribed to their low GB energy and diffusion coefficient, the fast GB migration velocity, and the discrete GB structure.