Effect of η-carbides on the microstructure and elevated-temperature tribological behavior of cobalt-based composites

(CoCrNiMoW)-WC composites were prepared by powder metallurgy. The microstructure, tribological properties and wear mechanisms of the composites were investigated at room temperature, 400 degree celsius, and 800 degree celsius. Multiple carbides are generated in situ in the sintered composites. Increased WC content enhanced the hardness and promoted the microstructural evolution of the composites. The phase composition of the composite changes from FCC phase + eta carbide to FCC phase + eta carbide + WC + Cr23C6, and the microstructure changes from individual island-like to connected island-like structure. High-temperature negative wear phenomena were observed in the 30 wt % and 50 wt % WC-added composites at 800 degree celsius, which contributed to the friction-induced high-temperature oxide volume increase compensating for the volume loss due to wear.