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The Influence of Prestrain on the Flow Stress Anomaly in TiAl Single Crystals

Published online by Cambridge University Press:  01 January 1992

M. A. Stucke
Affiliation:
Wright Laboratories, WL/MLLM, Wright-Patterson AFB, OH 45433-6533
D. M. Dimiduk
Affiliation:
Wright Laboratories, WL/MLLM, Wright-Patterson AFB, OH 45433-6533
P. M. Hazzledine
Affiliation:
UES, Inc., Materials Research Division, 4401 Dayton Xenia Rd., Dayton, OH 45432
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Abstract

Single crystal specimens of Ti44Al56, grown by the optical float zone method, were compression tested at room and elevated temperatures. The compression axis was close to [010] but the slip lines show essentially single slip. The material exhibits the anomalous yield behavior and a high work hardening rate. The work hardening rate at 1% strain is =3.5 GPa and is higher at 773K than at 296K. Specimens tested first at 773K and then at 296K retained their high temperature yield stress at the lower temperature, unlike Ll2 Ni3Al, but the work hardening rate was thermally reversible. The experiments suggest that the dislocations which first move at the yield point are 'permanently' locked at high temperature but that the dislocation interactions responsible for work hardening are characteristic of the deformation temperature.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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