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Simulation Of Dislocations In Ordered Ni3Al By Atomic Stiffness Matrix Method

Published online by Cambridge University Press:  15 February 2011

Y. E. Hsu
Affiliation:
State University of New York, Department of Mechanical and Aerospace Engineering, Buffalo, NY 14260
T.K. Chaki
Affiliation:
State University of New York, Department of Mechanical and Aerospace Engineering, Buffalo, NY 14260
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Abstract

A simulation of structure and motion of edge dislocations in ordered Ni3Al was performed by atomic stiffness matrix method. In this method the equilibrium positions of the atoms were obtained by solving a set of linear equations formed by a stiffness matrix, whose terms consisted of derivatives of the interaction potential of EAM (embedded atom method) type. The superpartial dislocations, separated by an antiphase boundary (APB) on (111), dissociated into Shockley partials with complex stacking faults (CSF) on (111) plane. The core structure, represented by the Burgers vector density distribution and iso-strain contours, changed under applied stresses as well as upon addition of boron. The separation between the superpartials changed with the addition of B and antisite Ni. As one Shockley partial moved out to the surface, a Shockley partial in the interior moved a large distance to join the lone one near the surface, leaving behind a long CSF strip. The decrease in the width of the APB upon addition of B and antisite Ni has been explained by a reduction of the strength of directional bonding between Ni and Al as well as by the dragging of B atmosphere by the superpartials.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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