Elastic to elastic-plastic transition of Al2O3/TiC ceramics studied by nanoindentation

In this work load-penetration curves obtained by nanoindentation were analyzed, using a spherical tip approximation and applying the stress/strain concept by Tabor. Nanoindentation experiments were done on sapphire, pure TiC, and a mixed ceramic with in situ formed TiCx layer, using a sharp cube-corner indenter at very low loads and penetration depths. With the implemented method it is possible to display the elastic to elastic-plastic transition of each investigated phase, and much more information can be extracted than by conventional analysis. Regarding the mixed ceramic, it was found that the present TiC phases exhibit slightly lower hardness than the alumina phase, but they can sustain much higher stresses during the transition from the elastic to the elastic-plastic regime. This is considered to be beneficial for the application as cutting material. No correlation was found between the nanomechanical behavior of the model materials sapphire and TIC and the corresponding phases of the mixed ceramic.