立方相对超细晶梯度硬质合金组织和性能的影响

Effect of Cubic Phase on Microstructure and Properties of Ultrafine Crystalline Gradient Cemented Carbides

以超细WC粉末为原料,采用低压预烧结和梯度烧结两步法制备了超细晶梯度硬质合金。通过添加不同的立方相,研究了立方相对超细晶梯度硬质合金组织和性能的影响。结果表明,仅添加Ti(C,N)可以形成较厚的梯度层,但梯度烧结后WC晶粒尺寸有较大的增长。(W,Ti)C和(Nb,Ta)C的加入不利于较厚梯度层的形成,但在梯度烧结过程中可以抑制WC晶粒的生长。添加(Ti,W)C的合金在梯度烧结后出现了少量尺寸大于1μm的WC晶粒,(Ta,Nb)C的加入可以很好地抑制合金中芯环结构立方相的形成。

With ultrafine WC powder as the starting material,ultrafine crystalline gradient cemented carbides were prepared by a two-step sintering process,in which the cemented carbides were lower pressure pre-sintered followed by gradient sintering.The influences of cubic phase on microstructure and property of the ultrafine crystalline gradient cemented carbides were studied.The results show that the thicker gradient layer can be formed in the alloy with adding Ti（C,N） only,but the mean WC grains size has a large value after gradient sintering.The thinner gradient layer has been formed when（W,Ti）C or（Nb,Ta）C is added,but the mean WC grains size is smaller than that of the alloy with adding Ti（C,N） only.Some WC grains with size above 1μm has been formed in the alloy with adding（W,Ti）C after gradient sintering.The formation of the core-rim structure cubic phase can be prevented by adding（Ta,Nb）C.