Application of EBSD to the evaluation of plastic deformation in the mechanical testing of WC/Co hardmetal

Abstract

Electron back scattered diffraction (EBSD) is an SEM based tool that provides orientation information from crystalline materials. This is achieved through the analysis of the reflection of electrons characteristic of particular crystal structures. As well as orientation information, because the quality of the orientation information depends on the perfection of the lattice at the point of interest, there is also potential for determining the degree of plastic deformation that is developed during the stressing of materials. EBSD was used in a preliminary evaluation of damage through two types of mechanical tests on a range of WC/Co hardmetals. These were compression fatigue tests on notched bars and model scratch tests on polished samples. In the compression fatigue tests the side face of notched fatigue samples that were exposed to compression fatigue were polished and subjected to EBSD analysis of the microstructure in a region close to the origin of fatigue cracks induced in the samples. Model scratch tests carried out with the NPL microtribology test system were also analysed by EBSD, and the results of the analysis related to the modes of damage observed by simultaneous high resolution SEM examination.