铬的添加量对WC-9Ni硬质合金微观结构与性能的影响

Effect of Additive Amount of Cr on Microstructure and Properties of WC-9Ni Cemented Carbides

摘要:

摘 要：本文以WC、Ni及Cr粉末为原料，采用传统粉末冶金方法制备了WC-9Ni-xCr系列硬质合金。利用扫描电镜、X射线衍射仪、机械性能检测设备和浸泡腐蚀测试方法等观察和表征了试样的微观结构、物理机械性能和耐浸泡腐蚀性能。结果表明：Cr的添加量对WC-9Ni硬质合金的微观结构与性能有着显著地影响。微量的Cr添加后，合金的WC晶粒长大被抑制，晶粒度出现下降；同时，合金的密度、抗弯强度下降，而硬度和耐中性水浸泡腐蚀性能（根据国际标准BS:6920:2000）得到提升。随着Cr添加量的进一步增加，合金的晶粒度、密度、硬度、强度和耐腐蚀性能等变化趋势放缓。另外，根据XRD、SEM和EDX等检测结果发现：过量的Cr粉添加后，WC-9Ni硬质合金的结构中倾向于形成一种新相——（Wx,Cr(1-x)）2C，这种新相易成为合金的断裂源。综合合金的微观结构和各项性能分析认为：当Cr粉添加量为1.2wt.%时，WC-9Ni合金具有相对最佳的综合性能。

Abstract:

Abstract: A a series of WC-9Ni-xCr samples were prepared through traditional powder metallurgy method. The effects of Cr additive amount on the microstructure and properties of WC-9Ni cemented carbides were investigated using X-ray diffraction, scanning electron microscope, mechanical property tester and immersion corrosion tests. The results show that the addition of Cr tends to inhibite the grain growth of the WC grains, decrease the density and bending strength of WC-9Ni cemented carbides, and increase the hardness and immersion corrosion resistant properties in neutral water of the alloys. With the Cr content increases, the variation tendency of grain size, density, hardness, bending strength and corrosion resistant of the alloy slow down. Furthermore, extensive addition of Cr in WC–9Ni cemented carbides could resulted in the formation of a new phase—(Wx,Cr(1-x))2C, which is easy to become fracture source of the alloy. Combine the results of microstructure and properties: sample 3# with Cr addition of 1.2 wt. % exhibits a relatively comprehensive performance in the five group of samples.