The objective of this work is mainly to elucidate the potential of TiAl type P/M alloys for higher temperature structural applications. TiAl alloys containing B-0.05% or Si-3% were previously reported to have a good combination of mechanical properties at high temperature. Therefore the high temperature oxidation behavior of TiAl alloys containing Si and B was investigated in this study.
The results were summarized as follows:
(1) Oxidation of TiAl type alloys substantially begins at 900°C or less, fairly sensitive to its alloying elements. Its oxidation resistance was increased by Si-addition up to 4.6% and decreased by B-addition of a few hundred ppm.
(2) Si-addition to TiAl alloy leads to less weight gain in the hot air of the range 1000-1100°C, mainly due to the protective alumina-like oxide formed on the surface layer.
(3) Siliconizing using the pack-cementation process improved the oxidation resistance of TiAl alloy by more than five times, probably relevant to the protective effect of stable silicides.