Abstract
Properties of WC-TiC-10% Co and β-10%Co alloys containing up to 20 mol% of various carbides, i.e., V4C3, Cr3C2, ZrC, NbC, Mo2C and TaC were studied at room temperature.
The results are as follows:(1) Grain size of the β-phase in β-10%Co alloy is increased by addition of Cr3C2 and V4C3, and is reduced by ZrC, NbC and TaC. Heterogeneous β-phase appears as the amount of ZrC increases. (2) The lattice parameters of β'-phase, i.e., carbide containing β-phase, increase with increasing ZrC, NbC and TaC but decrease sharply with addition of Cr3C2, V4C3 and Mo2C. (3) A large amount of Cr3C2 dissolves into the binder phase, but the other carbides are almost insoluble. (4) The hardness of the alloys is increased by ZrC and reduced by Cr3C2. (5) The strength of the alloys, which is higher in Ni binder than in' Co binder, is decreased remarkably by adding V4C3, Cr3C2 and ZrC, and is improved by Mo2C, NbC and TaC. The strength of the three phase (WC-β-γ) alloys is associated with that of two phase (β-7) alloys, suggesting that the strength of two or three phase alloy is controlled by that of β-phase or of β/γ interface.
