An Atomistic-to-Microscale Computational Analysis of the Dislocation Pileup-induced Local Stresses near an Interface in Plastically Deformed Two-phase Materials
An Atomistic-to-Microscale Computational Analysis of the Dislocation Pileup-induced Local Stresses near an Interface in Plastically Deformed Two-phase Materials
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DOI：
10.1016/j.actamat.2022.117663
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发表时间：
2022-01
期刊：
影响因子：
9.4
通讯作者：
Yipeng Peng;Rigelesaiyin Ji;T. Phan;Wei Gao;V. Levitas;Liming Xiong
中科院分区：
文献类型：
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作者：
Yipeng Peng;Rigelesaiyin Ji;T. Phan;Wei Gao;V. Levitas;Liming Xiong
以两相材料为模型系统，在这里，我们进行原子到微观尺度的计算分析如何位错堆积形成在掩埋界面通过二维并发原子连续模拟。一个新奇之处是在一个单一的模型中同时解决了微米级位错滑移，堆积引起的应力复杂性和原子级界面结构演化。我们的主要发现是：（i）当数十个位错参与堆积时，堆积引起的内应力范围可达数百纳米;（ii）由此产生的应力集中作为距离的函数衰减距堆积尖端的距离r，但偏离了基于Eshelby模型的1/r 0.5，其中假设界面是刚性的，不允许任何局部结构重建;只有当少量位错参与堆积时，堆积尖端的应力强度因子才与界面附近的位错密度成线性关系，而当数十个或更多位错到达界面时，应力强度因子会突然”上弯曲”到很高的水平。所获得的知识可以用来了解如何的局部应力可能会决定塑性流动引起的相变，孪生，或开裂的异质材料，如多晶钢，钛，镁，高熵合金，面心立方/体心立方，面心立方/六方晶系，和体心立方/六方晶系复合材料，含有高密度的接口。
Taking the two-phase material as a model system, here we perform atomistic-to-microscale computational analysis on how the dislocations pileup is formed at a buried interface through two-dimensional concurrent atomistic-continuum simulations. One novelty here is a simultaneous resolution of the μ m-level dislocation slip, the pileup-induced stress complexity, and the atomic-level interface structure evolution all in one single model. Our main findings are:(i) the internal stresses induced by a pileup spans a range up to hundreds of nanometers when tens of dislocations participate the pileup;(ii) the resulting stress concentration decays as a function of the distance, r, away from the pileup tip, but deviates from the Eshelby model-based 1/r 0.5, where the interface was assumed to be rigid without allowing any local structure reconstruction; and (iii) the stress intensity factor at a pileup tip is linearly proportional to the dislocation density nearby the interface only when a few dislocations are involved in the pileup, but will suddenly” upper bend” to a very high level when tens of or more dislocations arrive at the interface. The gained knowledge can be used to understand how the local stresses may dictate the plastic flow-induced phase transformations, twinning, or cracking in heterogeneous materials such as polycrystalline steel, Ti-, Mg-, high entropy alloys, fcc/bcc, fcc/hcp, and bcc/hcp composites, containing a high density of interfaces.