Microstructural evolution of FeCoNiCrMn high-entropy alloy subjected to laser shock peening: Molecular dynamics simulation study

Abstract

Molecular dynamics (MD) and Monte Carlo (MC) simulations are used to study the microstructural evolution of FeCoNiCrMn high-entropy alloys (HEA) after laser shock peening (LSP). The shock wave structure, microstructure, and dislocation evolution of single-crystal HEA after LSP are investigated at different shock velocities and shock directions. The elastic-plastic wave segregation of single-crystal HEA is observed at [110] crystal-direction shock. The cold fusion occurs in [110] and [111] crystal directions. After [001] grain direction shock, mainly the Hexagonal close-packed(HCP) phase is produced. The [110] and [111] grain directions mostly produce disordered structures aftershock. Lower-density dislocations are produced in the short-range ordered (SRO) model. A more complex microstructural evolution exists in nanocrystalline HEA due to the strong anisotropy of single-crystal HEA. A large number of stacking faults (SFs), twins, Hirth dislocation locks, and Lomer-Cottrell lock (LC) structures are generated. At the same time, nanocrystalline HEA produces a large number of dislocation entanglements near grain boundaries, leading to the precipitation of a large number of subgrains.