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

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 physicalmetallurgical properties and cutting conditions.This work investigated the physicalmetallurgical properties and micro-machinability of HEA FeCoNiCrAl x (x ¼ 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 FeCoNiCrAl x .FeCoNiCrAl 0.1 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 þ BCC) structure for FeCoNiCrAl 0.5 and FeCoNiCrAl 1 .The average microhardness values were approximately 183 HV, 294 HV, and 461 HV for FeCoNiCrAl 0.1 , FeCoNiCrAl 0.5 , and FeCoNiCrAl 1 , respectively.The increase in Al element content led to poor material machinability, in which FeCoNiCrAl 0.1 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.