The influence of yttrium addition on microstructure and wearability of WC78 TiC14 Co8 cemented carbide has been studied It is shown that the wearability of the carbide tool is significantly improved by adding trace amount of yttrium and the optimal adding amount is about 0 27%(wt)(in binder) Experimental results indicate that owing to adding yttrium, in as sintered cemented carbides the sizes of carbide grains and Co rich binder regions are reduced and their size homogeneity is improved, while in the binder, both dissolved contents of tungsten and titanium and volume proportion of the ductile α Co phase with f c c lattice are increased Therefore, the strength toughness of the binder and the cemented carbide which consists of the carbides and the binder are apparently enhanced Besides, it is found that many Y 2WO 6 particles appear along the WC/WC or WC/Co rich phase interfaces in as sintered carbide alloy with yttrium addition until 4 5%(wt), showing that during liquid phase sintering process of the alloys the segregation of yttrium atoms and Y 2WO 6 forming reaction might take place on the carbide particles/liquid binder interfaces, reducing the oxide films on the surface of WC particles and strengthening the cohesion of WC particles with Co rich binder