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Hrtem Studies of Dislocations and Interfaces in TiAl

Published online by Cambridge University Press:  10 February 2011

M. J. Mills ,
J. M.K. Wiezorek  and
H. L. Fraser
M. J. Mills
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
J. M.K. Wiezorek
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
H. L. Fraser
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
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Abstract

In this paper, we summarize the results of high resolution transmission electron microscopy investigations of the structure of dislocations and interphase boundaries in Ti-Al alloys. Dislocations of the type 1/2<110] and 1/2<112] have been examined in 60° and 90° orientations, respectively, in single-phase Ti-52 at%Al. The former dislocation exhibits an extremely compact core configuration, suggesting a high complex stacking fault energy, while the latter is dissociated the scale of several nanometers in a coupled intrinsic/extrinsic stacking fault configuration. Two types of α2/γ interface structures have been observed in nearly fully-lamellar Ti-48 at%Al. The first is consistent with the common observation of structural ledges due to 1/6<112> dislocations in the interface plane. The second interface type consists of a quasi-periodic array of 1/2<110] dislocations which do not lie in the interface, and appear to be contained wholy within the γ phase. The possible implications of these observations with respect to the mechanical behavior of both single-phase γ and two-phase lamellar microstructures are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 466: Symposium G – Atomic Resolution Microscopy of Surfaces and Interfaces , 1996 , 131
Copyright
Copyright © Materials Research Society 1997

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References

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