Dislocation motion in {gamma} TiAl by in situ straining experiments in the HVEM
- Max Planck Inst. of Microstructure Physics, Halle (Germany)
- Univ. of Birmingham (United Kingdom). School of Metallurgy and Materials
Micro-tensile specimens of coarse-grained Ti52at%Al crystals have been deformed in situ in a high voltage electron microscope at room temperature. In addition to some twinning, ``simple`` 1/2{l_angle}110] dislocations as well as super dislocations were moving, with the simple dislocations prevailing even if their orientation factor is lower than that of the super dislocations. Both types of dislocations are pinned, probably by small precipitates having a distance along the dislocations of about 100 nm. The precipitates consist most probably of Al{sub 2}O{sub 3}. Under stress, the dislocations bow out between the obstacles. The bowing is stronger for 1/2{l_angle}110] dislocations. An effective stress of about 41 MPa is estimated from their curvature. The kinematic behavior of the dislocations is in accord with precipitation hardening. The dislocations are generated by the double-cross slip mechanism. Their density within the slip bands corresponds to a long-range internal stress of about 40 MPa. These data are consistent with the flow stress of PST crystals in the easy orientation, taken from the literature.
- OSTI ID:
- 78305
- Report Number(s):
- CONF-941144-; ISBN 1-55899-265-0; TRN: IM9531%%356
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 28 Nov - 9 Dec 1994; Other Information: PBD: 1995; Related Information: Is Part Of High-temperature ordered intermetallic alloys VI: Part 1. Materials Research Society symposium proceedings Volume 364; Horton, J. [ed.] [Oak Ridge National Lab., Oak Ridge, TN (United States)]; Baker, I. [ed.] [Dartmouth College, Hanover, NH (United States)]; Hanada, Shuji [ed.] [Tohoku Univ., Sendai (Japan)]; Noebe, R.D. [ed.] [NASA Lewis Research Center, Cleveland, OH (United States)]; Schwartz, D.S. [ed.] [McDonnell Douglas Aerospace, St. Louis, MO (United States)]; PB: 713 p.
- Country of Publication:
- United States
- Language:
- English
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