立方相对超细晶梯度硬质合金微观组织的影响

Effect of cubic phase on microstructure of ultrafine crystalline gradient cemented carbide

摘要:

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1 μm的WC晶粒，(Ta,Nb)C的加入可以很好的抑制合金中芯环结构立方相的形成。

Abstract:

Ultrafine WC powder was chosed and ultrafine crystalline gradient cemented carbides was prepared by a two-step sintering process, where the cemented carbides is first lower pressure pre-sintered and then subjected to a gradient sintering. The influences of cubic phase on microstructure and property of ultrafine crystalline gradient cemented carbides have been studied. The results show that the thicker gradient layer can be form in alloy with only adding Ti(C,N), 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 was added, but the mean WC grains size is smaller than the alloy with only adding Ti(C,N). Some WC grains with size above 1 μm 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 prevent by adding (Ta,Nb)C.