Molecular dynamics simulation of complex alloy structures

Abstract

Developing realistic three-dimensional growth models for quasicrystals is a fundamental requirement. Uchida found a general principle for building crystal structures (the Uchida stacking motif) in complex alloys such as the μ-Al4Mn phase [1, 2]. Uchida stacking motif is illustrated in Fig. 1(a)-(c). It comprises three different types of layers-A, B and C-which are stacked in the order C B A B C. The A-layer is a close-packed layer with atomic vacancies. Atoms in the B-layer are located above and below the atomic vacancy sites in the A-layer, while atoms in the C-layer lie above and below interstices in the A-layer. The μ-Al4Mn phase is a representative approximant crystal, and its structure has a large hexagonal unit cell (with the space group P63/mmc, lattice constants a = 19.98 and c = 24.673 Å)(Fig. 1(d)). Here, we investigated the Uchida stacking motif using molecular dynamics (MD) simulations to search for clues to the origins of the atomic arrangements in quasicrystals.