High temperature oxidation of Ti-48%Al-2%W intermetallics

Powder metallurgically produced Ti-48%Al-2%W alloys were oxidized between 800 and 1050degreesC in air. The W-addition was quite effective in providing isothermal and cyclic oxidation resistance. The alloys oxidized parabolically up to 1050degreesC during isothermal oxidation, with small weight gains. The scales were adherent up to 900degreesC during cyclic oxidation. Oxide scales consisted primarily of an outer TiO2 layer, an intermediate Al2O3 layer, and an inner (TiO2+Al2O3) mixed layer. Tungsten was present below the intermediate Al2O3 layer, and also at the scale-matrix interface as W-enriched compounds. Below the oxide scale, a Ti3Al zone containing some W and O existed.