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Effect of Ordering Energy on Grain Boundary Structure in L12 Alloys

Published online by Cambridge University Press:  26 February 2011

G. J. Ackland  and
V. Vitek
G. J. Ackland
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA1 9104-6272
V. Vitek
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA1 9104-6272
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Abstract

Atomic structures of grain boundaries in two L12 ordered alloys with very different ordering energies have been calculated. The interatomic forces are represented by many-body empirical potentials based on the second moment approximation to the tight-binding density of states. Grain boundaries in strongly ordered alloys show very little relaxation. This results in the presence of columns of cavities in the boundaries. On the other hand boundaries in weakly ordered alloys, and also in pure f.c.c. materials, show extensive relaxations leading to much more homogeneous structures. We suggest that these structural features may be responsible for the intrinsic brittleness of grain boundaries in compounds such as Ni3Al in contrast with boundaries in pure f.c.c. metals or ordered alloys such as Cu3Au which are only embrittled by segregation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 133: Symposium H – High-Temperature Ordered Intermetallic Alloys III , 1988 , 105
Copyright
Copyright © Materials Research Society 1989

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References

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