Influence of hierarchical microstructure on mechanical properties in sintered CoCrFeMnNi high-entropy alloy fabricated by ultrasonic nanocrystalline surface modification

Abstract

Ultrasonic nanocrystal surface modification adopted in as-sintered porous CoCrFeMnNi high-entropy alloys reduces residual porosity and enhances mechanical properties. This treatment forms a gradient structure with a hardened surface and ductile core, achieving approximately reduced surface porosity by 75–78 %, increased yield strength by 106–119 %, and ultimate tensile strength by 15–22 %, respectively.