Hybrid Nanostructures and Stabilized Mechanical Properties of High‐Entropy Alloy Induced by Warm Laser Shock Peening

Abstract

Recently, the manufacture of high‐entropy‐alloy (HEA) parts by selective laser melting (SLM) has been extensively studied. However, the problems of high tensile residual stress, undesirable microstructure, and unstable mechanical properties in HEA parts caused by SLM process are difficult to be solved simultaneously. Herein, a warm laser shock peening (WLSP) process is used to obtain high strength, stable mechanical property, and favorable residual stress in SLMed FeNiCrCo HEA by regulating the microstructure in material. Experimental and simulation results show that WLSP treatment can induce high‐density dislocations and nanotwins in the HEA, resulting in a 39.4% increase in the surface strength of the HEA. Moreover, because of the high atomic kinetic energy brought by high temperature in WLSP processing, WLSP‐treated sample has higher density of dislocations and nanotwins than the sample treated by the LSP process at room temperature (RLSP), resulting in higher surface strength and better mechanical stability of the WLSP‐treated HEA. Meanwhile, the WLSP treatment enables the tensile residual stress generated in the SLM process to be transformed into compressive residual stress, which can enhance the fatigue performance of the HEA. Therefore, WLSP has great potential in obtaining SLMed HEAs with excellent mechanical properties.