复合添加Cr_3C_2/NbC对超细晶WC-10%Co硬质合金组织和性能的影响

Effects of Combined Addition of Cr_3C_2 and NbC on Microstructure and Properties of Ultrafine WC-10%Co Cemented Carbides

采用真空烧结方式制备超细晶WC-10%Co硬质合金,研究了复合添加晶粒长大抑制剂Cr3C2/NbC对合金组织及性能的影响。结果表明:在1400℃烧结条件下,添加剂的组成为0.4%Cr3C2+0.3%NbC时(文中含量均为质量分数),合金具有最好的综合力学性能,抗弯强度可达1951MPa、硬度1615HV30;WC平均晶粒尺寸为490nm。经SEM观察并通过EDS发现,抑制剂Cr3C2/NbC固溶到粘结相Co中,改变界面能,限制WC晶粒的长大;同时,也会降低WC在粘结相Co中的溶解度,从而起到细化晶粒的作用。

The ultrafine WC-Co cementd carbides were prepared by vacuum sintering technology,and the effects of codoped Cr3C2/NbC addition on microstructure and properties of the alloys are investigated.The results show that the alloy sintered at 1 400 ℃ with 0.4%Cr3C2＋0.3%NbC addition has the most comprehensive mechanical properties,the TRS is up to 1 951 MPa,the hardness is 1 615 HV30,and the average WC grain size is 490 nm.SEM and EDS obervation results show that WC grains are refined by the comprehensive effects of the Cr3C2/NbC dissolving in Co phase to alter the interface energy and to interfere the WC solution in the binder phase to prevent WC grain grow.