HEAT RESISTANT Ti ALLOY MATERIAL HAVING EXCELLENT HIGH TEMPERATURE CORROSION RESISTANCE AND OXIDATION RESISTANCE AND PRODUCTION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To impart excellent high temperature corrosion resistance and oxidation resistance to a heat resistant Ti alloy base material by forming an Al₂O₃ film which prevents the diffusion of Al from a protective film into a base material and the diffusion of components of the base material into an external layer, and has protective action in a self-healing manner.;SOLUTION: In the heat resistant Ti alloy material having high temperature corrosion resistance and oxidation resistance, a surface layer having a double layer structure consisting of an internal layer in which the three phases of a β phase, a γ phase and a Laves phase in a Ti-Al-Cr based alloy constitutional diagram are coexistent, and an external layer consisting of an Al-Ti-Cr based alloy is formed on the surface of a heat resistant Ti alloy base material, and the Al concentration in the external layer is ≥50 atomic %. The heat resistant Ti alloy base material is subjected chromium diffusion treatment in a β single phase region in a Ti-Al-Cr based alloy constitutional diagram. In a cooling stage, the γ phase and the Laves phase are precipitated from the β phase to form the internal layer in which the three phases of the β phase, γphase and Laves phase are coexistent. Next, diffusion treatment of aluminum is performed to form the external layer.;COPYRIGHT: (C)2004,JPO