Developing realistic three-dimensional growth models for quasicrystals is a fundamental requirement. The present work employs classical molecular dynamics simulations to investigate the adsorption of Al on a close-packed Al layer containing atomic vacancies. Simulation results show that the adsorbed Al atoms are located preferentially above and below the atomic vacancies in the close-packed layer, and the results obtained from a one-component system of atoms interacting via an interatomic pair potential for Al–Al appropriately reproduce the stacking motif seen in complex alloys such as the μ-Al4Mn phase. The simulations also reveal the formation of a deformed icosahedron. These results provide new insights into the growth mechanism and origin of complex alloys and quasicrystals.

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.