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.
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Ackland, G.J., Vitek, V. Effect of Ordering Energy on Grain Boundary Structure in L12 Alloys. MRS Online Proceedings Library 133, 105 (1988). https://doi.org/10.1557/PROC-133-105
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DOI: https://doi.org/10.1557/PROC-133-105