烧结温度对硬质合金梯度形成及晶粒生长的影响

Effect of sintering temperature on the gradient formation and grain growth of the hardmetals

以WC-10%Co硬质合金为研究对象,通过添加立方碳氮化物Ti(C,N)和(W,Ti)C,采用两步法烧结对硬质合金进行热处理,研究烧结温度对其梯度形成和晶粒生长的影响.结果表明,超细WC粉末经过真空预烧结后,合金的表层和芯部都均匀分布着硬质相WC、粘结相Co和立方相,且出现少量异常长大的WC晶粒;经过1460℃梯度烧结热处理后,合金表面无立方相,梯度层的厚度可达55μm,WC晶粒平均尺寸约为1.23μm,尤其是异常长大的WC晶粒数量和尺寸都显著增加.

Taking WC-10%Co hardmetals as the research object,by adding cubic carbonitrides Ti(C,N)and(W,Ti)C,the hardmetals was heat treated by two-step sintering method,and the effects of sintering temperature on the gradient formation and grain growth were studied.The results showed that after the ultrafine WC powder was vacuum pre-sintered,the surface layer and core of the alloy were evenly distributed with hard phase WC,binder phase Co and cubic phase,and a small amount of abnormally grown WC grains appeared.After 1460℃gradient sintering heat treatment,there was no cubic phase on the surface of the alloy,the thickness of the gradient layer could reach 55μm and the average size of WC grains was about 1.23μm,especially the number and size of abnormally grown WC grains were significantly increased.