Fracture toughness of WC-(4-20)%Ni alloys and WC-10%Ni alloys with different WC grain size (1.31-2.21μm) was compared with that of WC-Co alloy. Effect of various additions on the fracture toughness of WC-10%Ni alloy was also investigated.
The results obtained are as follows:
(1) Fracture toughness of WC-Ni alloy increases with the increase of the Ni content and the WC grain size.
(2) WC-Ni alloy shows a fracture toughness equal to WC-Co alloy in relation to hardness. However, for the same WC grain size, the WC-Ni alloy shows a lower hardness and a higher fracture toughness than those of WC-Co alloy. The reason is considered to be in that the binder phase of WC-Ni alloy has lower hardness and higher fracture toughness.
(3) By addition of Si, Ti, Cr and Mo which are soluble in Ni, the hardness of the WC-Ni alloy is increased. It is found that WC-Ni alloys containing 6%Si, 1-2%Ti, 5-10%Cr and Mo in the Ni binder show the same hardness and fracture toughness as the WC-Co alloy has.