Surface treatment method and a Ti-Al alloy obtained by those of Ti-Al alloy

摘要

PROBLEM TO BE SOLVED: To provide a surface treatment method for enhancing the high-temperature oxidation resistance of a Ti-Al-based alloy by a method suitable for the mass production, and the Ti-Al-based alloy.;SOLUTION: A Ti-Al-based alloy base material containing, by atom, ≥15% and ≤55% Al is heated and maintained in a gas atmosphere containing fluorine source gas; a fluorine-enriched layer of the thickness of ≥0.1 μm and ≤10 μm is formed on its surface; and the maximum concentration of F in the fluorine enriched layer is set to be ≥2% and ≤35%. Thus, the surface of the Ti-Al-based alloy base material is covered by an Al₂O₃ film with considerably low oxygen permeability when exposed to the high-temperature oxidizing atmosphere, showing the excellent high-temperature oxidation resistance. The poor high-temperature oxidation resistance which is the worst weakness of the Ti-Al-based alloy which is lightweight and high in high-temperature strength can be enhanced by a method suitable for the mass production. Thus, the alloy can be suitably applied to, for example, a turbine wheel for super charging, an engine valve, and a turbine blade of a gas turbine.;COPYRIGHT: (C)2009,JPO&INPIT