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Dislocation Interactions with Lamellar Grain Boundaries in Titanium Aluminum Intermetallics

Published online by Cambridge University Press:  15 February 2011

Jörg M. K. Wiezorek ,
Xiao-Dong Zhang  and
Hamish L. Fraser
Jörg M. K. Wiezorek
Affiliation:
Department of Materials Science & Engineering, University of Pittsburgh, 848 Benedum Hall, Pittsburgh, PA 15261
Xiao-Dong Zhang
Affiliation:
Reynolds Metals Company, 13203 N. Enon Church Road, Chester, VA 23836
Hamish L. Fraser
Affiliation:
Department of Materials Science & Engineering, Ohio State University, 2041 College Road, Columbus, OH 43210
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Abstract

The interactions of dislocations asscociated with deformation modes active in hard orientation compressed polysynthetically-twinned (PST) TiAl with lamellar boundaries have been studied by transmission electron microscopy (TEM). The deformation modes observed in the γ-phase involved soft superdislocation and hard ordinary dislocation slip, and hard twin systems. The transfer of these latter hard twin shears occurred across all types of lamellar (γ/γ)- and frequently across (γ/α2)-boundaries. Slip of superdislocations in the minority U2-phase lamellae has been shown to be associated with both direct transfer of piled-up twinning dislocation shears across the lamellar boundaries and the activation of interfacial sources due to pile-up stresses. The active deformation modes were consistent with macroscopic shape changes of the PST-TiAI when the various defect interactions with the lamellar boundaries and the proposed shear trasnfer processes were considered.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 578: Symposia A/C – Multiscale Phenomena in Materials - Experiments in Modeling , 1999 , 383
Copyright
Copyright © Materials Research Society 2000

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References

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