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Hydride structures in Ti-aluminides subjected to high temperature and hydrogen pressure charging conditionsThe distribution and chemistry of hydrides produced in single and dual phase alloys with a composition near TiAl have been investigated by using a combination of TEM and X-ray diffraction techniques. The alloys were exposed at 650 C to 13.8 MPa of gaseous H2 for 100 h. In the single-phase gamma alloy, large hydrides preferentially nucleated on the grain boundaries and matrix dislocations and a population of small hydrides was distributed throughout the matrix. X-ray and electron diffraction patterns from these hydrides indicated that they have an fcc structure with a lattice parameter of 0.45 nm. EDAX analysis of the hydrides showed that they were enriched in Ti. The hydrides were mostly removed by vacuum annealing at 800 C for 24 h. On dissolution of the hydrides, the chemistry of hydride-free regions of the grain boundary returned to the matrix composition, suggesting that Ti segregation accompanied the hydride formation rather than Ti enrichment causing the formation of the hydride.
Document ID
19910057545
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Legzdina, D.
(Illinois Univ. Urbana, IL, United States)
Robertson, I. M.
(Illinois Univ. Urbana, IL, United States)
Birnbaum, H. K.
(Illinois, University Urbana, United States)
Date Acquired
August 15, 2013
Publication Date
June 1, 1991
Publication Information
Publication: Journal of Materials Research
Volume: 6
ISSN: 0884-2914
Subject Category
Metallic Materials
Accession Number
91A42168
Funding Number(s)
CONTRACT_GRANT: NAG2-602
Distribution Limits
Public
Copyright
Other

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