Structure of icosahedral AlCuLi(Mg) alloys: modulated tiling model

Abstract

The structure and stability of icosahedral AlCuLi(Mg) alloyhas been investigated using molecular-dynamics simulations. The structural model is based on a 3D Penrose tiling with a slightly modified Henley-Elser decoration. Large periodic approximants of the quasicrystal (with more than 12000 atoms per cell) have been subjected to an isothermal molecular dynamics annealing with pseudopotential-derived interatomic forces. It is found that the quasicrystalline structure is stable, but the interatomic forces lead to a displacive modulation of the idealized structure. The calculated total and partial pair-correlation functions and diffraction patterns are in very good agreement with experiment; the analysis of the diffraction intensities yields a reliability-factor R ∼ 0.13.