WC-10%Co合金の諸性質と含有炭素量との関係

抄録

WC-10%Co alloys with various contents of carbon were prepared by the addition of sugar carbon to as-received WC powder and subsequent ball-milling and vacuum-sintering at 1370°∼1450°C for 1 hr followed by furnace cooling. The effect of the carbon content on the properties of the alloys such as hardness, transverse-rupture strength, density, grain size, electrical resistivity and its coefficient, lattice constant of binder phase, relative magnetic saturation, coercive force and microstructure were studied in detail. The main results obtained are as follows.
(1) All properties of the alloy vary characteristically with carbon content. (2) The strength of the alloy becomes a maximum, when the carbon content of the alloy in the two-phase range attains approximately a maximum (when at 6.15∼6.18 wt%C it is larger than the theoretical carbon content of WC). (3) Under this condition, for example, lattice constant of the binder and the electrical resistivity is at its minimum. (4) The narrow two-phase range corresponds to the width of about 0.15∼0.18 wt%C, which is wider than that induced from the result by J. Gurland⁽¹⁾. (5) The carbon content in cemented carbides is successfully controlled by adding free carbon to the powder as already mentioned.