稀土对锌熔法再生WC-8Co合金微观组织的影响

Influence of RE Additives on Microstructure of WC-8Co Hardmetals Produced from Zinc-Process Reclaimed Powder

以锌熔回收料为原料,用常规硬质合金生产工艺制备出再生WC-8Co硬质合金试样;用X射线衍射金相显微镜、场发射扫描电子显微镜/EDS能谱分析等测试方法研究了不同稀土钇添加方式制备的再生WC-8Co硬质合金孔隙、孔隙度、杂质形态及成分的差异,并采用截距法测量了WC晶粒尺寸及晶粒度分布。研究结果表明:添加稀土钇可抑制WC晶粒的非均匀长大,在一定程度上减小再生硬质合金的WC晶粒尺寸;可以显著减少再生硬质合金中的A类和B类孔隙,降低合金的孔隙度;稀土钇与杂质元素结合能够改善杂质相形态,由不规则和棒状Ca-S-O相转变为球状或类球形的Ca-Y-S-O相,并显著细化杂质相尺寸;采用复合粉的稀土添加方式使稀土钇元素分布更为均匀,微观组织和含稀土杂质相的均匀细化效果更加显著。

The regenerated WC-8Co hardmetal samples were fabricated by zinc-process reclaimed powder with conventional producing method. The morphology and composition of impurities, pore and porosity of regenerated WC-8Co hardmetals doped with different rare earth additives （RE） were studied by X-ray diffraction （XRD）, metalloseope, FESEM/EDS. Intercept method was used to measure the WC grain size and size distribution. The results showed that adding RE could reduce grain size of regenerated hardmetals and inhibit abnormal growth of WC grain, and significantly reduce the pore of class A and B and lower porosity; the combination of RE and impurity elements could transform the morphology of inclusions from large irregular and rod-like Ca-S-O phase to tiny spherical or spherical-like Ca-Y-S-O phase. RE could be more evenly distributed in regenerated hardmetals by using composite powder as RE dopant; the dimensions of WC and Ca-Y-S-O phase diminished more effectively.