High Temperature Oxidation of Ti-(43~52%)Al-2%W-(0~0.5%)Si Intermetallics

Intermetallics of TiAl-W-Si were oxidized isothermally and cyclically between 900 and 1050DGC in air. The oxidation resistance increased in the order of Ti43Al2W0.1Si, Ti48Al2W, Ti45 Al-2W0.5Si, Ti47Al2W0.5Si, and Ti52Al2W0.5Si. The scales consisted primarily of an outer TiO2 layer, an intermediate Al2O3 layer, and an inner (TiO2 + Al2O3) mixed layer. In those oxides, W and Si were present as dissolved ions. Silicon ions were present throughout the oxide layer, while W ions mainly below the intermediate Al2O3 layer. Also, W formed TixW1-x compounds in the oxygen-affected Ti3Al zone.