Healing performance of Ti2AlC ceramic studied with in situ microcantilever bending

Abstract

In situ microcantilever bending tests were carried out to evaluate the healing efficiency of pre-notched Ti2AlC ceramic after annealing at 1200 °C for 1.5 h. Microcantilevers of different orientations were fabricated with focused ion beam method at different locations, i.e. in a singular Ti2AlC grain, at a grain boundary or at the Ti2AlC–Al2O3 interface after healing. Ti2AlC microcantilever shows an anisotropic bending strength (ranging between 9.6 GPa and 4.6 GPa depending on the precise crystallographic orientations) that is closely related to the different atomic bonds in the layered structure. After healing, the Ti2AlC–Al2O3 microcantilevers exhibit almost the same strength of about 5.2 GPa, i.e. slightly higher than the cleavage strength (4.6 GPa) of the initial Ti2AlC microcantilevers. It suggests that the orientation of the matrix grain has no significant influence on the strength of healed microcantilevers. Furthermore, it turns out that the strength of the microcantilever with a healed grain boundary is at least twice the strength of the initial Ti2AlC cantilever with a grain boundary. It is concluded that the oxidation dominated self-healing mechanism of Ti2AlC ceramics can result in a perfect recovery of mechanical performance. The paper shows that the in situ microcantilever bending test provides a quantitative method for the evaluation of the strength of self-healing ceramics.