On the stability of {omega} phase in Ti-6-22-22S and Ti-6-4 alloys

Journal Article · Fri Aug 20 00:00:00 EDT 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00111-6· OSTI ID:691324

Zhang, X D; Baeslack, III, W A; Fraser, H L ^[1]; Wiezorek, J M.K. ^[2]; Evans, D J ^[3]

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1. Ohio State Univ., Columbus, OH (United States)
2. Univ. of Pittsburgh, PA (United States). Dept. of Materials Science and Engineering
3. Air Force Research Lab., Wright Patterson AFB, OH (United States). Materials and Manufacturing Directorate

Ti-6Al-2Mo-2Cr-2Sn-2Zr-0.2Si (Ti-6-22-22S) alloy, which was developed initially twenty years ago, has been recently reconsidered as a new moderate temperature material for aircraft structural applications. Ti-6-22-22S is stronger than the conventional Ti-6Al-4V (Ti-6-4) alloy and has better damage tolerance. As a part of the comprehensive program on the microstructural characterization of Ti-6-22-22S, the effect of heat treatment and the addition of small amounts of Si on the microstructural development and mechanical properties have been thoroughly investigated. These heat treatment conditions include variations in the cooling rates from the {beta} solution treatment and ({alpha}+{beta}) solution treatment, the temperatures of ({alpha}+{beta}) solution treatment and aging temperatures. Furthermore the microstructural stability of this alloy, particularly with respect to the precipitation of secondary intermetallic compounds and their effect on the mechanical properties, has been investigated. In previous studies, two types of precipitates, namely silicides and {alpha}{sub 2} phase, have been observed. The stability of these precipitates during long time aging, and partitioning of alloying elements as function of heat treatment as well as their effects on mechanical properties have also been reported. In the present study, observations of the {omega} phase and its stability will be reported for Ti-6-22-22S and the results will be compared with those reported for Ti-6-4 alloy.

• OSTI ID: 691324
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 6 Vol. 41; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
HEAT TREATMENTS
PHASE STABILITY
PHASE STUDIES
PRECIPITATION
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