Self-healing performance of Ti2AlC ceramic

Abstract

This work concentrates on revealing the oxidation-induced healing performance of Ti₂AlC. The microstructures of three kinds of defects: notches on single crystal, surface cavity and crack, after healing by oxidation in air at 1200 °C, were investigated in detail with the aid of scanning electron microscopy in conjunction with a focused ion beam cross-section milling technique. The notch-healing results demonstrate an effective healing effect due to the predominant Al₂O₃ phase filling in the notch with a dense microstructure. The microstructure of oxides filled in the surface cavity depends on the size and shape of the cavity. The largest cavity that can be healed at 1200 °C solely by Al₂O₃ is about 10 μm in width. A multi-layered microstructure of oxide scales was observed on the cleavage plane of Ti₂AlC grains, whereas the microstructure of oxides formed on the non-cleavage area was more complicated due to the anisotropic oxidation behavior of layered Ti₂AlC. The oxidation driven healing mechanism and factors affecting the healing efficiency of Ti₂AlC were discussed in detail.