Abstract
Two sorts of alloy systems, WC-TiC-16vol%Co and WC-TaC-l6vol%Co alloys having various amounts of TiC or TaC, were vacuum-sintered at 1400°C for 1 hr. The transverse-rupture tests were conducted according to JIS. The effect of addition of carbides on the strength of WC-16vol%Co alloy was studied, assuming that the strength is in close relation to the structural defects in sintered alloys. The method for the strength-analysis was the same as that previously reported by the present authors in WC-Co alloy.
The results obtained were as follows: (1) The strength of the present alloys was also confirmed to be directly controlled by the structural defects, in the same way as in WC-Co alloy. The defects such as pores, carbide-agglomerates and somewhat peculiar defects were generally observed in this case; the latter two sorts of defects were different from those developed in WC-Co alloy. (2) The strength of sound matrix (ao) (having none of defects) in WC-16vol%Co alloy decreased markedly by a small amount of TiC(TaC) addition, however the value of ao was assumed to be nearly the same in both the alloy systems under the same volume percentage of the β (TiC-WC solid solution) and TaC phases. It was also assumed that ao has values of about 300-450 kg/mm2 when the percentage exceeded about 20 vol%.
