Abstract
“Hardness” and “ductility” of brittel materials are addressed on the basis of energy principle for their surface deformation processes. Details of the hysteresis behavior associated with Vickers indentation loading-unloading process are studied. The hysteresis loop energy is related to the plastic/elastic deformation, hardness, and the ductility of brittle materials where a novel parameter, work-of-indentation, ΓI (J/m3), is defined and experimentally characterized as irreversible energy dissipation for the formation of unit indentation impression. The ΓI reduces to the hardness, H, for perfect plastic materials. The finite difference between ΓI, and H of brittle materials arises from the elastic recovery of surface deformation after indentation unloading. The physical meaning of the hardness of brittle meterials is scrutinized.
