纳米WC-Co硬质合金的微观组织特征

采用高能球磨工艺制备WC 10Co 0 8VC 0 2Cr2 C3纳米复合粉末,快速热压烧结制备纳米硬质合金块体,应用OM ,SEM ,TEM和EDXS观察合金的显微组织。观察发现纳米WC Co硬质合金的显微组织中粘结相呈空间网状结构贯穿于多边形状WC骨架空隙之间,在WC晶粒中观察到了呈团絮层状纳米析出相的存在,析出相为Co富集相,其形成机理是纳米WC Co材料结构失稳,在外加热场、压力场作用下诱发的相变行为

Microstructural Characterization of Nanostructured WC-Co Cemented Carbides

The powder of nanostructured WC-10Co-0.8VC-0.2Cr 2C 3 cemented carbides is prepared by high energy ball milling process, and then is treated by rapid hot pressing sintered to form the composite block, the microstructure of the composite is observed and investigated by means of optical microscopy, scanning electron microscopy, transmission electron microscopy and energy X-ray dispersive spectroscopy. In the microstructures, the binder phase is netlike dispersive and embedded in the gaps of polygonal WC grains. The cloud like nanosized precipitates inside WC grains are found in the microstructures of nanostructured WC-Co cemented carbides, and the nanoprecipitates are the cobalt-rich phase, they are formed by the mechanism of nanocrystalline WC-Co composites structure destabilization, the phase transformation behavior induced by thermal and pressure fields.