Preparation of a WC/Mo functionally graded material

WC powders have not been sintered by normal sintering and by hot press sintering without sintering additives. Spark plasma system (SPS) makes it possible to consolidate pure WC powders. The Vickers hardness and toughness of the dense WC were 24 GPa and 6 MPa . m(1/2). The hardness was 50% larger than that of WC-Co hard alloys, and the toughness is half. A functionally graded material (FGM) of WC and WC-Co or Mo can afford good hard materials with high hardness and toughness. WC/WC-CoFGM was not obtained, because Co diffused rapidly at high temperatures during the densification of a WC layer. Two graded layers were enough to relax the residual stress of WC/Mo FGM and prevent cracks.