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The interaction between dislocations and intergranular cracks

Published online by Cambridge University Press:  31 January 2011

H. Zhang
Affiliation:
Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794
A.H. King
Affiliation:
Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794
R. Thomson
Affiliation:
Center for Materials Science, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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Abstract

The elastic interactions of dislocations and intergranular cracks in isotropic materials have been studied. In the first part of the paper, a model based on the Rice–Thomson theory is established under which the conditions for dislocation emission and crack propagation can be described in terms of an emission surface, cleavage surface, and loading line in the local k-space associated with a mixed mode intergranular crack. For a given crack, the local k-field changes with the emission of dislocations from the crack tip, which alters the balance of cleavage and emission. In the second part, we present experimental results of in situ TEM observations of intergranular cracks in molybdenum. Alternating brittle crack propagation and dislocation emission is observed. The number of emitted dislocations corresponding to each crack propagation is in good agreement with the calculated values.

Type
Articles
Copyright
Copyright © Materials Research Society 1991

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