Self-healing performance of Ti2AlC ceramic

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 degrees 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 degrees C solely by Al2O3 is about 10 mm 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.