An atomistic-to-microscale computational analysis of the dislocation pileup-induced local stresses near an interface in plastically deformed two-phase materials

Xiong, Liming
Ji, Rigelesaiyin
Phan, Thanh
Gao, Wei
Levitas, Valery I.
Xiong, Liming
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Xiong, Liming
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Aerospace Engineering
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Mechanical Engineering
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Ames Laboratory
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Aerospace EngineeringMechanical EngineeringAmes Laboratory
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 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, , away from the pileup tip, but deviates from the Eshelby model-based , 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.
This is a manuscript of an article published as Peng, Yipeng, Rigelesaiyin Ji, Thanh Phan, Wei Gao, Valery I. Levitas, and Liming Xiong. "An Atomistic-to-Microscale Computational Analysis of the Dislocation Pileup-induced Local Stresses near an Interface in Plastically Deformed Two-phase Materials." 226 Acta Materialia (2022): 117663. DOI: 10.1016/j.actamat.2022.117663. Copyright 2022 Acta Materialia Inc. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission.
Dislocation pileup, Material interface, Stress concentration, Eshelby model, Molecular dynamics, Multiscale modeling