Directional solidification and microstructural control of the TiAl/Ti{sub 3}Al lamellar microstructure in TiAl-Si alloys
- Kyoto Univ. (Japan). Dept. of Materials Science and Engineering
Composite microstructures were grown from TiAl-Si alloys with the gamma/alpha2 lamellar microstructure aligned parallel to the growth direction by directional solidification techniques using a seed material. Within the composition range of 40--50 at% Al, the addition of Si to TiAl shifts the primary alpha region towards a much lower Al content. At a composition of Ti-43Al-3Si, either alpha or alpha2 can be stable, from melting temperature to room temperature and the orientation of the lamellar microstructure can be controlled using a seed material. In addition to the gamma/alpha2 lamellae, large Ti{sub 5}Si{sub 3} particles which formed from the liquid, and much smaller Ti{sub 5}Si{sub 3} particles which formed from an eutectoid reaction were observed. The room temperature mechanical properties were determined by tensile and three-point bend tests. From bend specimens oriented with the notch parallel to the lamellar microstructure, the Ti-43Al-3Si alloy was found to have a greater fracture toughness than a TiAl-PST crystal of the same orientation.
- OSTI ID:
- 271793
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 6 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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