326 金属間化合物TiAlの疲労き裂進展に及ぼす環境効果と昇温水素分析(OS1-5 環境・高温および熱疲労)(OS1 高強度材・表面改質材の疲労と破壊)  [in Japanese] 326 The effects of environment on fatigue crack propagation and thermal desorption spectroscopy in TiAl intermetallic compounds  [in Japanese]

The influence of environment on fatigue crack growth behaviour was investigated in nearly lamella and duplex titanium aluminides. The hydrogen evolution kinetics was analized by thermal desorption spectroscopy. When the cathodic charging is applied, the fatigue crack growth rate becomes higher than in dry air, in particular at higher stress intensity factor range. The hydrogen evolution rate is increased by cathodic charging, with lower temperature peaks and higher ones. The peaks at lower temperature are correlated with hydrides decomposition and detrapping of hydrogen from microstructual imperfections such as microvoides. As received materials also show an evolution peak at a higher temperature, and the evolution rate is independent of cathodic charging. In addition, the evolution rate at a higher temperature above 800℃ is increased by cathodic charging. These hydrogens are considered to have an important role on fatigue crack growth acceleration.