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Effect of Boron and Hydrogen on the Electronic Structure of Ni3Al

Published online by Cambridge University Press:  21 February 2011

N. Kioussis
Affiliation:
California State University Northridge, Department of Physics, Northridge, CA 91330
H. Watanabe
Affiliation:
California State University Northridge, Department of Physics, Northridge, CA 91330
R.G. Hemker
Affiliation:
California State University Northridge, Department of Physics, Northridge, CA 91330
W. Gourdin
Affiliation:
Lawrence Livermore National Laboratory, Department of Chemistry and Materials Science, Livermore, CA 94550
A. Gonis
Affiliation:
Lawrence Livermore National Laboratory, Department of Chemistry and Materials Science, Livermore, CA 94550
P.E. Johnson
Affiliation:
Lawrence Livermore National Laboratory, Department of Chemistry and Materials Science, Livermore, CA 94550
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Abstract

Using first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial boron and hydrogen on the electronic structure of the L12 ordered intermetallic Ni3A1. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound “pure” Ni3AI crystal: Charge is depleted at Ni and Al sites and enhanced in interstitial region. Substitution of Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between certain atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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