Microstructure and wear performance of a WC-8Co hard alloy modified using W powders doped with Y2O3

A modified WC-8Co hard alloy was prepared using W-Y2O3 powders as precursor materials. The composite powders was prepared using chemical deposition method and ball milling mixed process. The alloys was prepared using gas pressure sintering process. The microstructure of powders and alloys were characterized. Hardness, toughness and wearing behaviors were tested. The microstructure, composition and interface structure of the second phase except WC or Co in the modified alloy were analyzed. Results showed that the modified WC-8Co hard alloy had a regular grain shape and the comprehensive properties of the modified alloy was better than that of pure alloys. The second phase particles with a nano size were found inside and outside grains and their main ingredient was Y2O3. Y2O3 inside grains existed parallel planes with WC phases but the interface of Y2O3 on the grain boundary presented a V-shaped cross structure with WC phases. The second phase Y2O3 nanoparticles with intragranular and intergranular distribution increased the grain strength, refined the grain size, and exerted a pinning effect on the grain migration. Therefore, the mechanical properties of the modified hard alloy were improved, and the wear amount in the cutting experiment was reduced.