Laser additive manufacturing of FeCrCoMnNi high-entropy alloy: Effect of heat treatment on microstructure, residual stress and mechanical property

Abstract High entropy alloys (HEAs) have attracted much attention and been considered as novel materials with wide application prospects due to their outstanding comprehensive properties. With the development of laser processing technology, laser additive manufacturing (LAM) is regarded as a particularly feasible way to fabricate high entropy alloys. In this study, a relatively dense equiatomic FeCrCoMnNi high entropy alloy with excellent mechanical properties is manufactured by LAM successfully. Effect of heat treatment on phase, microstructure, microhardness, residual stress and mechanical properties of as-built (AB) specimens are investigated. The results show that the AB specimen exhibits a single FCC solid solution with mixed epitaxial grown dendrite columnar grain and equiaxed grain microstructure. After heat treatment, the dendritic microstructure of AB specimen evolves into recrystallized grain structure of HT-1100 specimen (heat treated at 1100 °C), while the crystalline structure is hardly changed. The AB specimen exhibits a superior microhardness and mechanical properties to that of the corresponding arc-melting specimen. The HTed specimen has much higher ductility than that of the AB specimen without distinct sacrifice of strength.