Mechanical properties and fracture characteristics of cemented tungsten carbide with fine microstructure studied by nanoindentation

Abstract

Nanoindentation was used to investigate mechanical properties and fracture characteristics of cemented tungsten carbide with fine microstructure. The elastic modulus and hardness of tungsten carbide grains were found to be significantly greater than those measured in cobalt binder rich regions, respectively. From the indented surfaces, very few evidences of cracking or fragmentation were observed using in-situ atomic force microscopy. However, the pop-in events were observed from the indentation load-displacement relationships and the acoustic emissions were detected during indenting processes, indicating the occurrences of brittle fracture. The latter observations were explained using a hypothesis that the fracture of the material under nanoindentation was mainly via sharp corner breaking due to the crash of individual tungsten carbide grains.