EBSD evaluation of damage in micro-tribology experiments on WC/Co hardmetals

Abstract

WC/Co hardmetals are used in many applications where resistance to abrasive wear is important. To provide further information on the mechanisms of damage that can occur in abrasion, a series of micro-tribology experiments were carried out on a number of WC/Co hardmetal samples. Samples were traversed under a diamond indenter with a sequence of controlled applied loads. The resultant damage was examined by scanning electron microscopy (SEM). Electron back scattered diffraction (EBSD) analysis of the damage was also carried out, both of the test surface, and also at some distance below the surface. To ensure that no damage was introduced to the structure of the materials, broad ion beam polishing was used to polish the original test surfaces and form the sub-surface section.It was found that plastic deformation of the WC grains and the Co binder phase occurred at all test loads. The visibility of slip increased with increasing test load, with fracture to the WC grains starting to occur at higher loads. EBSD analysis confirmed the trend for increasing plastic deformation with increasing load, but also showed that the degree of deformation had a strong relationship with orientation of the WC grains. Some transformation of the normal fcc Co phase to hcp was also detected close to the scratch path.