Removal and Fracture Characteristics of Cemented Tungsten Carbide under Nanoindenting and Nanoscratching

Nanoindenting and nanoscratching were used to investigate removal and fracture characteristics of cemented tungsten carbide (cWC). Nanoindentation results indicated that the elastic modulus and hardness of WC grains were significantly greater than those measured in cobalt binder rich regions, respectively. Few evidences of cracking or fracture were observed on the indented surfaces using both in-situ atomic force microscopy and scanning electron microscopy. However, the pop-in events were observed from indenting load-displacement curves and the corresponding acoustic emissions were detected, indicating the occurrences of brittle fracture. Nanoscratch results demonstrated that similar removal characteristics existed, but cracking was observed in both surface and subsurface of the scratched samples.