Microstructure and high-temperature tensile deformation of TiAl(Si) alloys made from elemental powders
- Zhejiang Univ., Hangzhou (China). Dept. of Materials Science and Engineering
- GKSS Research Center, Geesthach (Germany). Inst. of Materials Research
- Technical Univ. of Aachen (Germany)
Two ternary TiAl-based alloys with chemical compositions of Ti-46.4 at. pct Al-1.4 at. pct Si (Si poor) and Ti-45 at. pct Al-2.7 at. pct Si (Si rich), which were prepared by reaction powder processing, have been investigated. Both alloys consist of the intermetallic compounds {gamma}-TiAl, {alpha}{sub 2}-Ti{sub 3}Al, and {zeta}-Ti{sub 5}(Si, Al){sub 3}. The microstructure can be described as a duplex structure (i.e., lamellar {gamma}/{alpha}{sub 2} regions distributed in {gamma} matrix) containing {zeta} precipitates. The higher Si content leads to a larger amount of {zeta} precipitates and a finer {gamma} grain size in the Si-rich alloy. The tensile properties of both alloys depend on test temperature. At room temperature and 700 C, the tensile properties of the Si-poor alloy are better than those of the Si-rich alloy. At 900 C, the opposite is true. Examinations of tensile deformed specimens reveal {zeta}-Ti{sub 5}(Si, Al){sub 3} particle debonding and particle cracking at lower test temperatures. At 900 C, nucleation of voids and microcracks along lamellar grain boundaries and evidence for recovery and dynamic recrystallization were observed. Due to these processes, the alloys can tolerate {zeta}-Ti{sub 5}(Si, Al){sub 3} particles at high temperature, where the positive effect of grain refinement on both strength and ductility can be utilized.
- OSTI ID:
- 31975
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 3 Vol. 26; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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