Fe, V, B 添加 TiAl 合金の組織制御による常温引張特性の改善

概要

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A gamma TiAl alloy, Ti-46.7Al-1.3Fe-1.1V-0.35B(mol%) was developed as a casting material for turbine components, replacing superalloys. This alloy is characterized by the addition of Fe, V and B which improve castability. Analysis of X-ray diffraction patterns revealed the presence of the γ phase, the α_2 phase and the β phase. The β phase exists inherent in these alloying additions. This work has focused on the optimization of heat treatment conditions and metallurgical features to improve the room temperature tensile properties though understanding of the β phase in this alloy. On the basis of these experimental results, Fe and oxygen had a significant effect on the presence of the β phase. It was found that Fe works as strong β stabilizers and causes a peak in amount of the β phase at approximately 1250℃. We discussed the homogenizing conditions, followed the HIP treatment, to decrease the amount of the β phase. As a result, a heat treatment process has been developed to produce TiAl-Fe-V-B alloy with the duplex structure, which lead to a tensile strength of 550MPa and elongation of 1.8% at room temperature.
社団法人日本鉄鋼協会の論文
1998-05-01