Microstructure, Mechanical and Tribological Properties of Al_0.2Co_1.5CrFe_1.2Ni_1.5TiC_0.4 High Entropy Alloy

Al_0.2Co_1.5CrFe_1.2Ni_1.5TiC_0.4 high entropy alloy (HEA) was designed and then prepared by spark plasma sintering. Its microstructure, mechanical properties and tribological behaviors from room temperature to 800 ℃ were studied by X-ray diffractometer, scanning electron microscopy, energy dispersive spectroscopy, universal material testing machine, and high temperature tribometer. The results show that Al_0.2Co_1.5CrFe_1.2Ni_1.5TiC_0.4 HEA was composed of high entropy solid solution matrix phase with face-centered cubic (FCC) crystal structure and dispersively distributed TiC ceramic phase in the matrix. Moreover, FCC phase rendered HEA excellent ductility and toughness. TiC strengthening phase made HEA high hardness and strength. With the increase of temperature, the friction coefficients and wear rates decreased. Because of tribo-oxidation, a dense oxide glaze layer was formed on the worn surface at 800 ℃, which played an importent role of friction reduction and wear resistance and made HEA excellent high temperature tribological behavior.