摘要
采用在还原碳化法制备WC粉末前添加稀土氧化物Y2O3或CeO2,以及在WC与Co粉末混合球磨时加入该稀土氧化物两种不同的方式,在WC-10Co硬质合金中添加稀土元素,利用金相显微镜和扫描电镜观察稀土硬质合金的组织形貌与显微结构,采用X射线衍射仪(XRD)和电子探针对合金的相成分与微区成分进行分析,并测试合金的硬度、断裂韧性与磁性能,研究稀土及其添加方式对硬质合金结构与性能的影响。结果表明,无论以何种方式添加Y2O3或CeO2,最终制备的硬质合金中稀土元素都与氧共存,并以球形颗粒的形式弥散分布于硬质合金的钴粘结相中。稀土硬质合金中WC晶粒球化趋势明显,WC/WC的邻接度由0.6降低至0.39,断裂韧性由12.8 MPa?m1/2提高至16.7 MPa?m1/2。球形、弥散分布的稀土氧化物颗粒会破坏合金结构的连续性,导致合金强度降低。
The rare earth WC-10Co cenmented carbides were prepared by introducing Y2O3 and CeO2 before preparing tungsten carbide powders or ready-to-press （RTP） mixing powders. The morphology and microstructure of WC-Co cenmented carbide were observed by optical metallographic and scanning electron microscope. Phase compositions were identified by X-ray diffraction and the micro-region composition analyses were carried out on an electron probe micro-analyzer. The hardness, rupture toughness and magnetic properties were tested for investigating the effects of rare earth and their adding ways on microstructures and properties of the cemented carbides. The results show that, for both the two adding ways, rare earths accompany oxygen in the prepared cemented carbides and are dispersed in cobalt binder in the form of spherical particles. WC grains in rare earth cemented carbides show the evidently trend of spheroidization, which can result in the decrease of WC/WC contiguity from 0.6 to 0.39 and lead to the improvement of fracture toughness from 12.8 MPa＆#183;m1/2 to 16.7 MPa？m1/2. The strength decreases because that the spherical and dispersed rare earths oxygen particles can destroy the continuity of the cemented carbides structure.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2014年第5期701-706,共6页
Materials Science and Engineering of Powder Metallurgy
基金
国家科技重大专项(2012ZX04012021-01)
关键词
稀土
硬质合金
显微结构
邻接度
rare earth
hardmetal
microstructure
contiguity
