Orientation relationships between silicides and other phases in a Ti-45at.%Al-2.7at.%Si alloy
- Aachen Univ. of Technology (Germany)
- Zhejiang Univ., Hangzhou (China)
Si-containing TiAl alloys consist of three phases: {gamma}-TiAl, {alpha}{sub 2}-Ti{sub 3}Al and {zeta}-Ti{sub 5}(Si,Al){sub 3}. It has been reported that primary {zeta}-Ti{sub 5}(Si,Al){sub 3} precipitates during solidification of cast alloys or during HIP-treatment of elemental powder processed materials, whereas secondary {zeta}-Ti{sub 5}(Si,Al){sub 3} precipitation at boundaries of {alpha}{sub 2}/{gamma}-lamellae takes place in high temperature tensile and creep experiments. TEM investigations of the orientation relationship of secondary {zeta}-Ti{sub 5}(Si,Al){sub 3} silicides in the lamellar region of Ti-4.5at.%Al-2.7at.%Si alloy have been performed. The results obtained can be summarized as follows: Secondary silicide precipitates can form at both {alpha}{sub 2}/{gamma} and {gamma}/{gamma} boundaries, but were found mostly at {alpha}{sub 2}/{gamma} boundaries. These silicides tend to grow into {alpha}{sub 2}-Ti{sub 3}Al laths. Reasons are as follows: (1) {zeta}-Ti{sub 5}(Si,Al){sub 3} had the tendency to consume {alpha}{sub 2}-Ti{sub 3}Al, and (2) the crystallographic structure of {zeta}-Ti{sub 5}(Si,Al){sub 3} is similar to that of {alpha}{sub 2}-Ti{sub 3}Al.
- OSTI ID:
- 103571
- Journal Information:
- Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 4 Vol. 33; ISSN SCRMEX; ISSN 0956-716X
- Country of Publication:
- United States
- Language:
- English
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