Abstract
The WC-TaC-Co alloys containing less than 5%TaC (sintered at 1350°C or 1400°C for lhr) were used as specimens. Their hardness, transverse-rupture strength, density and microstructures were examined, and the effects of the abnormal structure, i.e., spotty structure of tantalum carbide phase on the mechanical properties were studied. Main results obtained were as follows :
(1) The abnormal structure was observed only in the WC-TaC-Co alloys containing a small amount of tantalum carbide. In WC-TaC-10% Co and WC-TaC-20%Co alloys, the said structure was observed when the tantalum carbide content was less than about 0.9%o and 1.6%, respectively.
(2) Hardness and density of the alloy were not affected but transverse-rupture strength was sharply reduced by the formation of the abnormal structure.
(3) Therefore, it was shown that the decrease in strength must be taken into consideration in the preparation of WC-TaC-Co alloys containing a small amount of tantalum carbide.
