Elsevier

Acta Materialia

Volume 45, Issue 10, October 1997, Pages 3949-3962
Acta Materialia

Microscopic model for directional coarsening of precipitates in alloys under external load

https://doi.org/10.1016/S1359-6454(97)00116-XGet rights and content

Abstract

We carried out computer simulations of a binary alloy decomposition in two dimensions under external stress using a Metropolis exchange dynamics with an effective long-range, anisotropic, “spin” Hamiltonian. This was obtained by minimizing the energy of elastic interactions A and B atoms of unequal size, over the displacement of atoms from the equilibrium lattice sites. The evolution of configurations and the elastic strains associated with them were studied for various initial states. Directional coarsening was clearly visible in the precipitate morphology and was measured quantitatively both in the structure function and in the amount of interface pointing in the x or y direction. These were found to saturate at a fixed ratio, independent of the initial configuration: be it disordered or consisting of perfect stripes. This is due to an apparently inherent “waviness” of the precipitate interfaces. A suitably defined mean domain size increases with time in a manner consistent with a tα behavior, with α between 1/4 and 1/3.

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    Present address: Department of Physics, Virginia Polytechnic Institute, Blacksburg, VA 24061-0435, U.S.A.

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