MoFe1.5CrTiWAlNbx refractory high-entropy alloy coating fabricated by laser cladding

Abstract

To obtain excellent performance of cutting-tool-coating materials, the MoFe1.5CrTiWAlNbx (x = 1.5, 2, 2.5, 3; x values in molar ratio) high-entropy alloy (HEA) coating was designed and fabricated on M2 tool steel by laser cladding. The microstructure, phase structure, microhardness and wear resistance were investigated by XRD, SEM, TEM, microhardness tester and wear machine, respectively. The experimental results show that the coating mainly consists of BCC, (Nb, Ti) C as well as C14-Laves phase. When x = 1 and 2, respectively, the microstructure of the coating is composed of cellular crystal, on which exists particle carbide; as x = 2.5 and 3, respectively, the microstructure transforms into the columnar crystal, on which a number of particle carbide occurs. The microhardness of the coating increases gradually as the increase of Nb content, when x = 3, the microhardness reaches a maximum of HV 910, which is far higher than that of substrate, and the wear resistance becomes best. The wear mechanism of coating is mainly abrasive wear.