Transformations in {alpha}{sub 2} + {gamma} titanium aluminide alloys containing molybdenum. Part 2: Heat treatment
Journal Article
·
· Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
- Defence Metallurgical Research Lab., Hyderabad (India)
The response of as-cast structures of 12 alloys in the Ti-Al-Mo system containing 44 to 50 at. pct Al and 2 to 6 at. pct Mo to simple single step heat treatments in the temperature range 1,373 to 1,673 K is described. The microsegregation patterns present in the cast structure persist to a large extent after heat treatment, especially below 1,673 K. However, tentative conclusions regarding phase equilibria in this temperature and composition range are drawn from the results. High-temperature equilibria are dominated by the {beta}, {alpha} + {beta}, and {alpha} + {gamma} phase fields, while the {beta} + {gamma} phase field dominates equilibrium below 1,473 K. Three major types of transformation behavior are observed: a massive {alpha} to {gamma} transformation, which occurs within the {alpha} phase on quenching from 1,673 and 1,573 K in alloys centered around the 48 pct Al composition; a eutectoid transformation from {alpha} to B2 + {gamma} mixtures, which occurs at 1,473 K and below in alloys centered around the 48Al-4Mo and 46Al-6Mo compositions; direct {gamma} precipitation in {beta}, which occurs primarily in the 44Al-6Mo composition at 1,273 K and below; and finally growth of {gamma} lamellae in {alpha} + {gamma} structures with B2 precipitation on lamellar interfaces, which occurs over a broad range of alloy compositions and temperatures.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 544051
- 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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