The response of porous Al2O3 probed to nanoindentation

The response of porous Al2O3 to nanoindentation was investigated at microscopic scales (nm–μm) and under ultra-low loads from 5 to 90 mN with special attention paid to the dependence of the load–depth behaviour to sample porosity. It was found that the load–depth curves manifest local responses typical of the various porous structures investigated. This is particularly clear for the residual deformation after load removal. Similarly, the limited mean pressure of the sample containing small grains and interconnected pores is consistent with its porous structure. By comparison, the samples with larger grain size and various porous structures exhibit higher pressures and smaller residual deformations that can be attributed to the mechanical response of the solid phase.