Physical-metallurgical properties and micro-milling machinability evaluation of high entropy alloy FeCoNiCrAlx

Abstract

High-entropy alloy (HEA) belongs to the emerging multi-principal alloy with excellent mechanical-physical properties. The material machinability is critical for cutting planning, especially for novel materials with various chemical compositions and mechanical properties. The machinability of high-entropy alloys mainly depends on the physical-metallurgical properties and cutting conditions. This work investigated the physical-metallurgical properties and micro-machinability of HEA FeCoNiCrAlx (x = 0.1, 0.5, 1) with vacuum arc melting preparation. Experimental results indicated that the difference of Al element content affected the chemical element distribution, phase composition, microstructure, and microhardness of prepared HEA FeCoNiCrAlx. FeCoNiCrAl0.1 appeared single face-center-cubic (FCC) structure, while the increase in Al element content led to dual face-center-cubic and body-center-cubic (FCC + BCC) structure for FeCoNiCrAl0.5 and FeCoNiCrAl1. The average microhardness values were approximately 183 HV, 294 HV, and 461 HV for FeCoNiCrAl0.1, FeCoNiCrAl0.5, and FeCoNiCrAl1, respectively. The increase in Al element content led to poor material machinability, in which FeCoNiCrAl0.1 had better machinability due to lower micro-milling forces, more stable cutting process, lower specific cutting energy, better surface qualities and smaller tool wear. This work combined the prepared material properties and micro-machinability evaluation to guide HEA design and select practical machining parameters.