The mechanical properties of α-Al2O3(00▪1) were investigated by using the technique of nano-indentation with a Berkovich indenter. Coupled with Hertzian contact theory, a theoretical shear strength of 28GPa was determined from the onset of pop-in events on load-displacement curves during loading, and an intrinsic hardness of 30GPa was obtained by analysis of the so-called indentation size effect; based upon the concept of geometrically necessary dislocations. The predicted values of the shear strength, hardness and elastic modulus were in good agreement with available experimental data. The importance of experimentally calibrating the area function over the contact depth range, prior to nano-indentation tests, was emphasized.

Nanoindentation-Induced Elastic-Plastic Transition and Size Effect in α-Al2O3(00▪1). C.Lu, Y.W.Mai, P.L.Tam, Y.G.Shen: Philosophical Magazine Letters, 2007, 87[6], 409-15