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Fragmentation of α2 Plates in a Fully Lamellar TiAl During Creep

Published online by Cambridge University Press:  10 February 2011

J. G. Wang ,
L. M. Hsiung  and
T. G. Nieh
J. G. Wang
Affiliation:
Chemistry & Materials Science, Lawrence Livermore National Laboratory, P. 0. Box 808, L-370, Livermore, CA 94551–9900, U.S.A.
L. M. Hsiung
Affiliation:
Chemistry & Materials Science, Lawrence Livermore National Laboratory, P. 0. Box 808, L-370, Livermore, CA 94551–9900, U.S.A.
T. G. Nieh
Affiliation:
Chemistry & Materials Science, Lawrence Livermore National Laboratory, P. 0. Box 808, L-370, Livermore, CA 94551–9900, U.S.A.
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Abstract

The fragmentation and spheroidization of α2 laths in a fully-lamellar TiAl alloy during creep were examined. Three possible mechanisms, Rayleigh's perturbation model, subgrain boundary groove mechanism and intersection of deformation twins with α2 lamellae were presented and discussed. During creep deformation, the pile-up of interfacial dislocations leads to a change of planar interface, which, in turn, causes a difference in local chemical potential, and further results in the spheroidization of α2 lamellae. On the other hand, the deformation of the α2 phase is expected to be induced by the high local stress concentration introduced by the pile up of interfacial dislocations. The dynamic recovery process may lead to the formation of subgrain boundaries in the α2 lamellae, which results in the spheroidization and termination of α2 lamellae with the aid of diffusion during creep.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 552: Symposium KK – High-Temperature Ordered Intermetallic Alloys VIII , 1998 , KK8.20.1
Copyright
Copyright © Materials Research Society 1999

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