超细硬质合金WC-8Co-0.8(Cr_3C_2/TaC)的组织与性能

以超细WC-8Co硬质合金为研究对象,混合添加晶粒长大抑制剂Cr3C2/TaC。结果表明,合金在添加0.8wt%Cr3C2/TaC时的TRS达到3675MPa,而在添加0.5wt%和1.0wt%Cr3C2/TaC时的TRS降到2120MPa;Cr3C2/TaC在很大程度上影响了合金烧结时的致密化,WC-8Co-0.8wt%(Cr3C2/TaC)压坯在1400℃下完全致密化需要的烧结时间为60分钟;而同类普通WC-8Co-0.8wt%(Cr3C2/TaC)的压坯,由于没有超细粉末的高表面能,烧结60分钟后密度只能达到理论密度的98.8%;TaC和Cr3C2对W在γ相中的固溶度具有相反的作用。

Structure and Performance of Ultra Fine Cemented Carbides WC-10Co-0.8 (Cr3C2/TaC)

The ultra-fine WC-8Co cemented carbides are studied in this paper and Cr3C2/TaC as co-addition grain inhibitors. Transverse rupture strength of the ultra fine WC-8Co alloy in 0.8wt%(Cr3C2/TaC)reaches 3675MPa but it is only 2120MPa in 0.5wt% and 1.0wt%Cr3C2/TaC. The additions of grain growth inhibitors Cr3C2/TaC make cemented carbides alloy densification decreasing in 1400℃. Full densification of the ultra fine WC-8Co-0.8wt% (Cr3C2 /TaC) green compacts need 60 minutes in sintering temperature. The common homogeneous cemented carbides are only 98.8% theoretical density in 60 minutes. The reason may be the powders of ultra fine cemented carbides have high specific surface energy. TaC and Cr3C2 have opposing actions on the solid solubility of W in γ phase. That is to say that the lack of carbon in alloy caused by the addition of Cr3C2 will lead to a tendency of WC grain discontinuous growth.