Phase transformation in the nitride layer during the oxidation of TiAl-based alloys

The orientation relationship (OR) between the TiN and Ti2AlN phases in the nitride layer during the oxidation of TiAl-based alloy at 900 °C was determined by transmission electron microscopy (TEM). The OR is (1 1 1)TiN ∥ (0 0 0 1)Ti2AlN, [01¯1]TiN∥[112¯0]Ti2AlN. Al can reduce the twin boundary energy of TiN, leading to the formation of many stacking faults in the Al-enriched TiN phase. The Ti2AlN phase forms at the bottom of the TiN phase when the Al content is sufficient to induce phase transformation. Phase transformation was identified in the Ti2AlN phase after electron irradiation for about 40 s.