Microstructure and mechanical properties of additively manufactured CrMnFeCoNi high-entropy alloys after ultrasonic surface rolling process

Abstract

CrMnFeCoNi high-entropy alloy (HEA) were prepared using laser additive manufacturing (LAM) technology, and the surface was subjected to ultrasonic surface rolling process (USRP). The purpose was obtaining enhanced HEA through USRP. A nanocrystalline (NC) layer was obtained on the HEAs surface, and it was found that dislocation activity was the main reason for grain refinement, which resulted in a large number of low-angle grain boundaries on the surface. With the appearance of the NC layer, the maximum hardness of HEAs reached 352.28 HV, which was almost 1.5 times that of LAM sample, the surface hardness reached 5.2 GPa, which much higher than LAM sample. Due to the high hardness, the USRP sample shows a low coefficient of friction and loss, showing better wear resistance.