Experimental observations on the accomodation dislocation pattern for a low symmetry gradient orientation

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The accommodation dislocation pattern for a concentration gradient oriented along a low symmetry direction (approximately [013]) has been characterized by standard transmission electron microscopy techniques. A number of interesting features were found, including extensive node reactions, a large screw component, dislocation lines lying out of the isoconcentration planes, and broken mirror plane symmetry. In situ hot-stage electron microscopy has been used to study the evolution of the dislocation pattern. The observed migration directions of the dislocations are not parallel to the gradient direction. A cooperative mechanism was observed by which the dislocation network could be translated by a double node reaction. © 1989.

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Materials Science and Engineering A