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Slip of low-angle tilt grain boundary (110) in FCC metals at perpendicular shear
International Journal of Plasticity ( IF 9.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.ijplas.2020.102843
Eugeniy V. Fomin , Alexander E. Mayer

Abstract Grain boundaries (GBs) make a significant contribution into the kinetics of plastic deformation of both polycrystalline and nanocrystalline metals. Among others, motion of GBs is an important phenomenon, which has to be taken into account in the consideration of the thermo-mechanical response of poly- and nanocrystals. In this work, we study motion of low-angle tilt GBs and the accompanying relaxation of shear stresses in the case, when the shear is applied perpendicular to GB. Using the molecular dynamics (MD) simulations, we consider bicrystals made of aluminum, copper and nickel as FCC metals with different stacking fault energies. MD data are used for construction and verification of a GB motion model, which is based on the previously proposed equation of motion of a solitary dislocation in a single crystal. Within this model, a low-angle tilt GB is presented as a wall of periodically located perfect edge dislocations. The main driving factors are the external shear stress and the local stress distribution due to the plastic relaxation in the trace of each dislocation creating an area of partially relaxed stresses behind the shifted GB. These factors define the average GB velocity during the main stage of motion, while dislocation-dislocation interactions between the walls and inside each wall define details of the motion, such as the curvature of GBs and their mutual acceleration at the late stage of interaction of two approaching opposite GBs.

中文翻译:

垂直剪切下 FCC 金属中低角度倾斜晶界 (110) 的滑移

摘要 晶界 (GBs) 对多晶和纳米晶金属的塑性变形动力学做出了重大贡献。其中,GBs 的运动是一个重要的现象,在考虑多晶和纳米晶的热机械响应时必须考虑到这一点。在这项工作中,我们研究了当剪切垂直于 GB 时,低角度倾斜 GB 的运动以及在这种情况下剪切应力的伴随松弛。使用分子动力学 (MD) 模拟,我们将铝、铜和镍制成的双晶视为具有不同层错能的 FCC 金属。MD 数据用于构建和验证 GB 运动模型,该模型基于先前提出的单晶中孤立位错运动方程。在这个模型中,低角度倾斜 GB 表现为周期性定位的完美边缘位错的墙。主要的驱动因素是外部剪切应力和局部应力分布,这是由于每个位错轨迹中的塑性松弛造成的,在移位的 GB 后面形成了一个部分松弛的应力区域。这些因素定义了运动主要阶段的平均 GB 速度,而壁之间和每壁内部的位错 - 位错相互作用定义了运动的细节,例如 GB 的曲率及其在两个相互作用后期的相互加速度接近对面的 GB。主要的驱动因素是外部剪应力和局部应力分布,这是由于每个位错轨迹中的塑性松弛造成的,在移位的 GB 后面形成了一个部分松弛的应力区域。这些因素定义了运动主要阶段的平均 GB 速度,而壁之间和每壁内部的位错 - 位错相互作用定义了运动的细节,例如 GB 的曲率及其在两个相互作用后期的相互加速度接近对面的 GB。主要的驱动因素是外部剪应力和局部应力分布,这是由于每个位错轨迹中的塑性松弛造成的,在移位的 GB 后面形成了一个部分松弛的应力区域。这些因素定义了运动主要阶段的平均 GB 速度,而壁之间和每壁内部的位错 - 位错相互作用定义了运动的细节,例如 GB 的曲率及其在两个相互作用后期的相互加速度接近对面的 GB。
更新日期:2020-11-01
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