Microstructural and mechanical characterisation of WC-Co alloys elaborated by liquid phase sintering and hot isostatic pressing: study of WC crystallites size evolution

This work aims at the characterisation and study of WC tungsten carbide crystallites size evolution as well as of the microstructure of WC-Co alloys produced by liquid phase sintering and by hot isostatic pressing (HIP). The goal of this study is to demonstrate a possible improvement in mechanical and surface properties by using hot isostatic pressing (HIP) compared to liquid phase sintering. Two types of cemented carbides containing 11 and 20 wt-% of cobalt have been produced by two different techniques. The alloys microstructures were characterised by scanning electron microscopy (SEM). The size evolution and dimensions of WC crystallites were derived from Wagner-Halder and Williamson-Hall methods following the exploitation of X-ray diffraction line profiles. Vickers micro-hardness tests were also performed in this study. It is found that there is a clear improvement in micro-hardness for materials densified by hot isostatic pressing (HIP).