Abstract
Cemented carbides containing 15 vol.% of Co and 10 wt.% of TaC or TiC in total carbides were vacuum-sintered and two kind of specimens having different carbon content respectively in each alloy were obtained. Some properties of these alloys affected by low temperature annealing at 700°C and 800°C were mainly studied in comparison with those of straight WC-Co alloys to get an information on the influences of TaC or TiC in the cemented carbides. Brief conclusions of this experiment were as follows: (1) Transverse-rupture strength and magnetic saturation of the alloys containing TaC or TiC increase with increasing of carbon content of the alloys, in the phase range corresponding to two phase range of straight alloys, but on the contrary, hardness, specific resistivity and lattice constant of the binder phase decrease. (2) After annealing, rupture strength, specific resistivity, magnetic saturation and lattice constant of the binder decrease and the change of these properties is in general remarkable in low carbon alloys than in high carbon. (3) The phenomena above mentioned are in good agreement with those of WC-Co straight alloys. So the change of properties by annealing is considered also due to the fact that the W atoms highly dissolved in the binder phase of low carbon alloys precipitate during the course of the anealing, as already reported on the WC-Co alloys. (4) The rate of the precipitation, however, will decrease by the addition of TaC or TiC to the WC-Co alloys.
