Effect of initial microstructure on the compactability of rapidly solidified Ti-rich TiAl powder
- Kumamoto Univ., Kurokami, Kumamoto (Japan). Dept. of Materials Science
Initial microstructure dependence of compactability at elevated temperature in rapidly solidified Ti-rich TiAl alloy powders produced by plasma rotating electrode process (PREP) has been investigated. There were two kinds of powders with respect to the microstructure. The first one had a surface relief of a martensitic phase, which was referred as M powder. The second one had a dendritic structure, which was referred as D powder. {alpha}{sub 2}+{gamma} microduplex and {alpha}{sub 2}/{gamma} lamellar structures were formed in M and D powders of the Ti-40 at%Al alloy by heat treatment at 1,273 K, respectively. The microduplex structure consisted of {gamma} precipitate in the twin related {alpha}{sub 2} matrix with the usual orientation relationship. It was difficult to compact the D powder by hot pressing at 1,273 K under 50 MPa for 14.4 ks. On the other hand, the M powder was compacted easily by hot pressing with the same condition. The twin related {alpha}{sub 2} and {alpha}{sub 2} boundary changed to random ones and the {alpha}{sub 2} and {gamma} phases lost the usual orientation relationship in the duplex structure during the hot pressing. In other words, the low energy boundaries were changed to the high energy ones suitable for grain boundary sliding. Dislocations were scarcely observed inside of both the {alpha}{sub 2} and {gamma} crystal grains. It was concluded that the grain boundary sliding was a predominant deformation mode in the M powder during the hot pressing. D and M powders in Ti-45 and 47 at%Al alloys showed the same tendency as those in Ti-40 at%Al alloy during hot pressing.
- OSTI ID:
- 571701
- Report Number(s):
- CONF-961202-; TRN: IM9806%%47
- Resource Relation:
- Conference: 1996 Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 2-6 Dec 1996; Other Information: PBD: 1997; Related Information: Is Part Of High-temperature ordered intermetallic alloys VII; Koch, C.C. [ed.] [North Carolina State Univ., Raleigh, NC (United States)]; Liu, C.T. [ed.] [Oak Ridge National Lab., TN (United States)]; Stoloff, N.S. [ed.] [Rensselaer Polytechnic Inst., Troy, NY (United States)]; Wanner, A. [ed.] [Univ. Stuttgart (Germany)]; PB: 799 p.; Materials Research Society symposium proceedings, Volume 460
- Country of Publication:
- United States
- Language:
- English
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