Dynamic Vickers indentation of brittle materials

Static and dynamic Vickers indentations were performed on brittle materials to investigate the rate effects in hardness, induced crack morphologies, and fracture toughness. The dynamic indentations were performed on a hardness tester, which utilizes elastic stress wave propagation phenomena in a slender rod that can deliver indentation loads of 100 μs durations. Under dynamic indentations, an increase in hardness was observed in all the brittle materials compared to their static hardness measurements. Analysis of the evolved crack morphology revealed an increase in fracture toughness for zirconia ceramics and a decrease in fracture toughness for pyrex glass under dynamic indentations. The implications of the rate dependence of hardness and fracture toughness on material removal mechanisms are discussed.