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Core Structure And Mobility Of a <101] Dislocations In L10 TiAl

Published online by Cambridge University Press:  22 February 2011

S. Rao
Affiliation:
UES, Inc.; Dayton, OH 45432
C. Woodward
Affiliation:
UES, Inc.; Dayton, OH 45432
J. Simmons
Affiliation:
NRC Research Associate, WL/MLLM, WPAFB, OH 45433
D. Dimiduk
Affiliation:
WL/MLLM, Materials Directorate, Wright Laboratory, WPAFB, OH 45433
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Abstract

An empirical atomistic potential, fit to the structural and elastic properties of L10 TiAl within the embedded atom method (EAM), is used to simulate the mobility of two possible planar forms of a<101] dislocations in a model L10 compound. The two configurations examined were: the planar SISF-APB-CSF coupled (P core) and the decomposed 1/2<110]-SISF-SESF coupled (D core). Six different line orientations are considered for the P core: 0° (screw), 30°, 60°, 90° (edge), 120° and 150°. The ‘ideal’ friction stress at 0°K of a<101] dislocations in the P form is found to be a function of line orientation, with the close packed line directions, <101] (screw) and <110] (60°), having friction stresses ranging from 0.001–0.002μ. Previously calculated results on the friction stress of a/2<110] dislocations, using an identical potential are consistently higher than the friction stress of a<101] dislocations. Simulations of the interaction of glide strains with the D core for the 60° (line directions < 110]) and 120° (line directions <011]) orientations show that the Shockley partial trailing the SESF in the D core is strongly pinned. The dislocation moves by extension of SESF when glide stresses are applied with SESF as the trailing fault.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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