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Structure and Energetics of Vacancies, Antisites and Divacancy Complexes in the Ni-Al system

Published online by Cambridge University Press:  01 January 1992

Zhao Yang Xie
Affiliation:
Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
Diana Farkas
Affiliation:
Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
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Abstract

We studied the energetics and structure of simple point defects and defect clusters in the Ni-Al system. Atomistic computer simulation was used for this purpose with embedded atom interatomic potentials. In both, Ni3Al and NiAl the energetics are such that excess Ni is accommodated by anitisite defects more easily than excess Al. Structural vacancies are therefore more likely with stoichiometry deviations in the Al-rich side than in the Ni-rich side. The interaction of vacancies of different types to form divacancies was studied. Several configurations were found with a very similar energy to that of the two monovacancies far apart. Some configurations show attraction and others show repulsion. The vacancy interaction distance is limited to a few interatomic distances.

The relaxation around these defects was studied in detail and the results can be interpreted in terms of the larger size of the Al atom.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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