Hydrogen occlusion and hydride formation in titanium aluminides
- Naval Air Warfare Center, Warminster, PA (United States)
- Lehigh Univ., Bethlehem, PA (United States). Dept. of Mechanical Engineering and Mechanics
- Univ. Twente, Enschede (Netherlands)
A systematic investigation of hydrogen occlusion and hydride formation in titanium aluminides was conducted to develop a better understanding of hydrogen interaction with gamma-based titanium aluminide alloys. Aluminum compositions ranging from 25 to 53.5 at% were used to cover both single phase {alpha}{sub 2}-Ti{sub 3}Al and {gamma}-TiAl and two-phase ({alpha}{sub 2}+{gamma}) alloys. Hydrogen was introduced by gas phase charging at a pressure of 0.1 MPa and temperatures from 425 to 800 C. Hydrogen occlusion varied by over two orders of magnitude in these alloys, with the maximum and minimum in Ti-25Al ({alpha}{sub 2}-Ti{sub 3}Al) and Ti-53.5Al ({gamma}-TiAl) alloys, respectively, and in between for the two-phase ({alpha}{sub 2}+{gamma}) alloys. Hydrides were observed to form in the Ti-25Al and Ti-30Al alloys, while none were detected in the Ti-36Al and {gamma}-TiAl based alloys. A model is proposed on the basis of the interstitial-site-blocking theory to account for the observed reduction in hydrogen occlusion and reduced tendency for hydride formation, and is discussed in relation to the experimental results on the single phase alloys. For the two-phase ({alpha}{sub 2}+{gamma}) alloys, occlusion depended on the fraction of each phase and followed the rule of mixtures.
- OSTI ID:
- 225081
- Report Number(s):
- CONF-950201--; ISBN 0-87339-304-X
- Country of Publication:
- United States
- Language:
- English
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