WC-Ni-Fe-Mo硬质合金的微观结构与性能研究

Investigation on Microstructure and Properties of WC-Ni-Fe-MoCemented Carbides

摘要:

本文采用低压烧结的方式制备了性能良好的 WC–Ni–Fe–Mo 硬质合金，研究分析了不同 Mo 添加量对 WC–Ni–Fe硬质合金组织性能的影响。结果表明：不同 Mo 添加量对 WC–Ni–Fe 硬质合金的微观结构与性能有着显著地影响。添加微量的 Mo 可以抑制 WC-Ni-Fe 硬质合金中 WC 晶粒的溶解再析出长大，一定程度上可以细化 WC 晶粒。随着 Mo 在 WC–Ni–Fe 合金中的含量增加，合金孔隙率逐渐下降。密度先下降后升高，而抗弯强度的变化趋势则相反。当 Mo 添加量较少时，合金的硬度较为稳定，抗弯强度明显提升，而断裂韧性逐渐降低；当 Mo 添加量较大时，合金的硬度、抗弯强度降低，而断裂韧性上升。当 Mo 的添加量为0.5 wt %时，合金具有最佳的力学性能，可与同比例 Co 含量的 WC–Co 硬质合金相媲美，其维氏硬度为 HV 1460、抗弯强度为 4245 MPa、断裂韧性为 17.01 MPa·m1/2。

Abstract:

WC–Ni–Fe–Mo cemented carbides with fine properties were prepared by low pressure sintering. The effects of Mo content on the microstructure and properties of WC–Ni–Fe–Mo cemented carbides were analyzed in detail. The results show that the addition of Mo has obvious influence on WC–Ni–Fe cemented carbides. The addition of Mo can refine WC grains to a certain extent by inhibiting the dissolution and precipitation of WC grains in WC–Ni–Fe cemented carbides. With the increase of the of Mo content, the porosity of the alloys decrease gradually. The density of alloys first decreased and then increased, while the bending strength had the opposite trend. When a trace amount of Mo was added, the hardness of alloys was relatively stable, ?the bending strength increased obviously，the fracture toughness had a gradually decreased. When the addition of Mo contents further increased, the hardness and bending strength were both decreased, and the fracture toughness increased. WC–Ni–Fe–Mo cemented carbide with 0.5 wt% Mo had the optimum properties, which can comparable to those of WC–Co cemented carbides with the identical binder ratio. The maximum value of its hardness, bending strength and fracture toughness were HV 1460, 4245 MPa, 17.01 MPa·m1/2, respectively.