Microstructure and properties of CoCrFeNiAlx (x = 0.1, 0.5, 1) high-entropy alloys enhanced by laser surface remelting.

In this study, CoCrFeNiAl x (x = 0.1, 0.5, 1) high-entropy alloys (HEAs) are prepared using vacuum arc melting. In order to improve the surface properties of CoCrFeNiAl x HEAs, their microstructure is manipulated by laser surface remelting (LSM). The microstructure, the mechanical properties, and the corrosion resistance of the HEAs before and after LSM are studied systematically. The microstructural analysis reveals that the LSM-samples contained either a single FCC phase (CoCrFeNiAl 0.1 and CoCrFeNiAl 0.5) or a mixture of BCC + B2 phases (CoCrFeNiAl 1) with refined grains. Moreover, BCC precipitates and a spherical nano-dispersed phase (B2) are detected in the surface layer of CoCrFeNiAl 0.5 and CoCrFeNiAl 1 , respectively. The mechanical properties of CoCrFeNiAl x alloys are found to be significantly enhanced after LSM, which is mainly ascribed to the generation of the BCC phase, dislocation reinforcement and grain-strengthening as well as precipitation hardening. The electrochemical measurements confirm that all samples (after LSM) have a positive potential and a lower current density in 3.5 wt% NaCl solution compared to the untreated sample. The results indicate that LSM can help homogenize the structure and improve the properties of CoCrFeNiAl x HEAs. [Display omitted] • LSM treatment was conducted on the surface of as-cast CoCrFeNiAlx (x = 0.1,0.5,1) HEAs and the grains of each component were refined obviously. • A 365.2–1200 μm thick remelted layer was formed. • After LSM, abundant dislocation structures appeared on the surface, and spherical nano dispersed B2 phase was found in Al 1. • Surface microhardness, wear and corrosion resistance were improved evidently. [ABSTRACT FROM AUTHOR]