The microstrcture and high-temperature oxidation resistance of tungsten carbide with high entropy alloys as binder

Abstract

High-entropy alloys (HEAs) hold promise for achieving excellence performance due to unconventional composition and structure. In this paper, the effect of FeCoCrNiAl HEAs as binder instead of Co on the microstructure of WC cemented carbide was investigated. The isothermal oxidation resistance of the WC-HEAs cemented carbides with 6, 10, 15 % was studies at 700, 800, 900 and 1000 °C. The results revealed that the microstrcture of WC-HEAs cemented carbides was dense, and the average grain sizes of WC decreased with the increase of HEAs binder content. The oxide layers containing WO3, NiWO4, and a small amounts of MWO4 (M = Co, Cr) were formed after high-temperature oxidation of WC-HEAs cemented carbides, the ratio of MWO4-to-WO3 in the WC-HEAs oxide layer increases gradually as oxidation temperature increase. The oxide films thickness of WC-10HEAs cemented carbides became thinner than that of WC-10Co at 900 °C. The oxidation kinetic curves also demonstrated that the oxidation resistance of the WC-HEAs cemented carbides was better than that of WC-Co cemented carbide except that the binder content was 6 %, and the oxidation resistance of the WC-HEAs cemented carbide was superior to WC-Co cemented carbide, which was attributed to the formation of protective oxides and MWO4 tungstate.