Atomistic simulation of deformation behaviors polycrystalline CoCrFeMnNi high-entropy alloy under uniaxial loading

YM Qi and HM Xu and TW He and M Wang and ML Feng, INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, 95, 105415 (2021).

DOI: 10.1016/j.ijrmhm.2020.105415

Molecular dynamics is used to examine the evolution of dislocations and FCC -> HCP phase transformation, as well as deformation twinning for a typical polycrystalline CoCrFeMnNi high-entropy alloy. It is found the discrepancy of the stress-strain curve for tension and compression owing to the strength mechanism during deformation. The grain refinement behavior is only observed in samples of compression, which leads to the difference of flow stress compared with the tension. At the early plastic stage, FCC -> HCP phase transformation is the major deformation behavior. Three paths of FCC -> HCP phase transformation for inducing plasticity are analyzed, and the mechanism of spontaneous nucleation of stacking faults is the mainly approach to the transformation. For large strain, the pattern of twinning induced plasticity plays a critical role on the plastic deformation of the HEA. The results are qualitatively consistent with experiments and provide a fundamental understanding of plastic deformation in FCC polycrystalline CoCrFeMnNi HEA.

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