Patent ID: 7097685

Claim:
A cemented carbide comprising: a binder phase consisting essentially of an iron family metal, a first hard phase consisting essentially of WC having a hexagonal crystal structure, and a second hard phase consisting essentially of one or more types of a compound of a metal or metals of group 4, 5 or 6 of the periodic table having an NaCl cubic crystal structure; wherein, the cemented carbide is formed by a surface region with a thickness of 2 to 50 μm consisting of the binder phase and the first hard phase, and an inner region present underneath the surface region consisting of the binder phase, the first hard phase and the second hard phase, a ratio of an average grain size of the first hard phase in the surface region to an average grain size of the first hard phase in the inner region is less than 1, and a ratio of an area of the binder phase in the surface region to an area of the binder phase in the inner region is greater than 1.