Extracting uniaxial responses of single crystals from sharp and spherical hardness measurements

This investigation provides a mechanistic background to mechanical property extractions performed from single-crystal microhardness measurements. The analysis concerns both spherical and sharp (pyramidal) indentations. We show that the uniaxial stress–strain curves inferred from hardness measurements in single crystalline units of material are coincidental with those attained under true uniaxial loadings along specific crystalline orientations. Landmark hardness relations that were originally developed for power-law strain hardening polycrystalline aggregates are extended to single-crystal indentations. Mechanical property extractions in crystals violating power-law hardening because of a marked critical resolved shear stress and/or extreme strain hardening saturation are subsequently addressed. The analysis is pertinent to the assessment of multiple-glide deformation stage-II and strain hardening saturation stage-III of cubic single crystals from indentation experiments.