Effect of a Long-Range Dislocation Pileup on the Atomic-Scale Hydrogen Diffusion near a Grain Boundary in Plastically Deformed bcc Iron
Effect of a Long-Range Dislocation Pileup on the Atomic-Scale Hydrogen Diffusion near a Grain Boundary in Plastically Deformed bcc Iron
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DOI：
10.3390/cryst13081270
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发表时间：
2023-08
期刊：
影响因子：
2.7
通讯作者：
Yipeng Peng;Rigelesaiyin Ji;T. Phan;Xiang Chen;Ning Zhang;Shuozhi Xu;A. Bastawros;Liming Xiong-Liming-Xio
中科院分区：
文献类型：
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作者：
Yipeng Peng;Rigelesaiyin Ji;T. Phan;Xiang Chen;Ning Zhang;Shuozhi Xu;A. Bastawros;Liming Xiong-Liming-Xio
本文采用原子连续（CAC）方法模拟了氢（H）在体心立方铁中沿着晶界扩散的过程。在保留微尺度位错滑移和晶界处原子结构演化的情况下，我们的主要发现是：（i）在含氢晶界附近数十个位错的堆积可以产生高达3GPa的局部内应力，（ii）在晶界处堆积的位错越多，滑移-晶界交叉点前的氢扩散越慢;和（iii）H原子在堆积尖端后面快速扩散，被捕获在GB内，并且在堆积尖端前面缓慢扩散。CAC模拟预测的局部H扩散率Dpileup−tip和局部应力σ相互关联。然后，我们巩固这样的相关性到一个力学模型，考虑作为Eshelby夹杂物的位错堆积。这些发现将为研究人员提供机会：（a）表征塑性、氢扩散和氢诱导裂纹（HIC）下裂纹萌生之间的相互作用;（B）开发用于扩散-塑性耦合模型的基于机制的本构规则，以理解连续介质水平上材料中机械和质量传输之间的相互作用;以及（c）将多晶材料的原子变形物理学与它们在水性环境中的性能相联系，这在实验中目前难以实现。
In this paper, we present concurrent atomistic-continuum (CAC) simulations of the hydrogen (H) diffusion along a grain boundary (GB), nearby which a large population of dislocations are piled up, in a plastically deformed bi-crystalline bcc iron sample. With the microscale dislocation slip and the atomic structure evolution at the GB being simultaneously retained, our main findings are: (i) the accumulation of tens of dislocations near the H-charged GB can induce a local internal stress as high as 3 GPa; (ii) the more dislocations piled up at the GB, the slower the H diffusion ahead of the slip–GB intersection; and (iii) H atoms diffuse fast behind the pileup tip, get trapped within the GB, and diffuse slowly ahead of the pileup tip. The CAC simulation-predicted local H diffusivity, Dpileup−tip, and local stresses, σ, are correlated with each other. We then consolidate such correlations into a mechanics model by considering the dislocation pileup as an Eshelby inclusion. These findings will provide researchers with opportunities to: (a) characterize the interplay between plasticity, H diffusion, and crack initiation underlying H-induced cracking (HIC); (b) develop mechanism-based constitutive rules to be used in diffusion–plasticity coupling models for understanding the interplay between mechanical and mass transport in materials at the continuum level; and (c) connect the atomistic deformation physics of polycrystalline materials with their performance in aqueous environments, which is currently difficult to achieve in experiments.