Room-temperature dislocation activity during mechanical deformation of polycrystalline ultra-high-temperature ceramics

Ceramics such as ZrB2 and HfB2 are potential candidates for ultra-high-temperature applications. Their electrical conductivity values are comparable to those of metals. Such unusual electrical properties arise from the presence of metallic bonds in their crystal structure. We argue that the metallicity in chemical bonding is also reflected in their room-temperature mechanical deformation, which was investigated through indentation-induced slip bands and the resulting dislocation activity. These observations were rationalized on the basis of metallic character of their dislocation core structure.