| The oxidation kinetics of TiAl alloys with and without 3, 5 and 10 wt.% additions of Si₃N₄ particles were studied between 900 and 1100℃ in atmospheric air. The Si₃N₄ dispersoids effectively increased the oxidation resistance of TiAl alloys, the more pronouncing the more Si₃N₄ dispersoids were added. The oxide scales formed on pure TiAl alloys were primarily composed of TiO₂and some Al₂O₃, whereas those formed on TiAl-Si₃N₄ alloys consisted of TiO₂, Al₂O₃, and SiO₂. The increased oxidation resistance of TiAl-Si₃N₄alloys compared with Si₃N₄-free TiAl alloys was mainly attributed to; (i) increased scale adherence via stabilized, refined oxide grains, (ii) thin scale formation owing to the presence of silica phase and the promotion of Al₂O₃-rich scale formation. |
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