板状WC晶粒WC-(Co-Ni)硬质合金的组织和性能

采用真空烧结法制备了板状WC晶粒WC-(Co-Ni)硬质合金,通过XRD、SEM、EDS等手段研究了Ni/(Ni+Co)比对硬质合金组织和性能的影响规律。结果表明:随着Ni/(Ni+Co)比的增大,硬质合金显微组织中板状WC晶粒的比例逐渐减少,硬质相颗粒的尺寸逐渐增大且平均长厚比逐渐减小。当Ni/(Ni+Co)比过大时,硬质合金中硬质相颗粒出现了团聚现象,使其力学性能显著降低。当Ni/(Ni+Co)比为0.3和0.5时,WC-(Co-Ni)硬质合金的综合力学性能较高,这与其硬质相颗粒较细和平均长厚比较大有关。当Ni/(Ni+Co)比为0.5时,WC-(5Co+5Ni)硬质合金具有较优的综合力学性能,其抗弯强度、硬度和断裂韧性分别为2 448 MPa、90.0HRA、21.2 MPa·m~(1/2)。

Microstructure and Properties of WC-(Co-Ni) Cemented Carbides with Plate-like WC Grains

WC-(Co-Ni) cemented carbides with plate-like WC grains were produced by vacuum sintering.The effectsof Ni/(Ni+Co) ratio on the microstructure and mechanical properties of WC-(Co-Ni) cemented carbides were studied by X-ray diffractometry (XRD),scanning electron microscopy (SEM) and energy dispersive spectrdmeter (EDS).The results showed that with the increasing Ni/(Ni+Co) ratio,the ratio of plate-like WC grains in the microstructure of cemented carbides decreased,the sizes of hard phase particles gradually increased,and the average length-thickness ratio of hard phase particles gradually decreased.When the Ni/(Ni+Co) ratio was too high,the hard phase particles in cemented carbides were merged together,resulting in an obvious decrease of its mechanical properties.As the Ni/(Ni+Co) ratio was 0.3 or 0.5,WC-(Co-Ni) cemented carbides exhibited good mechanical properties,which was related to the smaller hard phase particles and bigger average length-thickness ratio of hard phase particles.WC-(Co-Ni) cemented carbides with Ni/(Ni+Co) ratio of 0.5 exhibited better mechanical properties,the TRS,hardness and K1c were 2 448 MPa,90.0HRA,21.2 MPa · m1/2,respectively.