Transformations in {alpha}{sub 2} + {gamma} titanium aluminide alloys containing molybdenum. Part 1: Solidification behavior
- Defence Metallurgical Research Lab., Hyderabad (India)
The solidification structures of 12 alloys in the Ti-Al-Mo system with Al contents ranging from 44 to 50 at. pct and Mo contents ranging from 2 to 6 at. pct have been characterized metallographically and, for composition gradients, by electron probe microanalysis. All alloys solidify dendritically through sequences that fall into four distinct categories: alloys that solidify completely into the {beta} phase field, alloys that solidify first into an L + {beta} phase field and finally into an {alpha} + {beta} phase field through an L + {beta} + {gamma} region, alloys that solidify first into a L + {beta} phase field and finally form {alpha} + {beta} + {gamma} structures, and alloys that solidify into a L + {alpha} phase field. Postsolidification transformations occur as consequence of transitions from the high-temperature {beta}, {alpha} + {beta}, and {alpha} + {gamma} phase fields to low-temperature {alpha} + {beta} + {gamma} or {beta} + {gamma} region. A variety of phase distributions result, such as Widmanstaetten {alpha}{sub 2} + B2 structures from the {alpha} {yields} {alpha} + {beta} reaction followed by ordering, lamellar {alpha}{sub 2} + {gamma} structures from the {alpha} {yields} {alpha} + {gamma} reaction followed by ordering of the {alpha} phase, eutectoid B2 + {gamma} structures from the {alpha} {yields} B2 + {gamma} reaction, and platelike {gamma} structures from the {beta} {yields} {beta} + {gamma} reaction. The former are observed in Al lean alloys, while the latter are present in Mo rich alloys.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 544050
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 9 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
- Country of Publication:
- United States
- Language:
- English
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