Molecular dynamics simulation of mechanical properties of decagonal quasicrystal approximate phase Al2Fe

Abstract

By using the molecular dynamics method, the tensile and elastic mechanical properties of Al2Fe (tI6 and oF24) alloys for decagonal quasicrystals approximation are simulated. Structural models for tI6 and oF24 are first established and then the appropriate embedded atom method (EAM) potential function is selected to analyze the effects of temperature and strain rate on the stress-strain relation, atomic structure and deformation mechanism. Furthermore, all the elastic constants Cij of tI6 and oF24 are calculated by the molecular dynamics explicit deformation method, and the crystal structure and stability of tI6 and oF24 are also judged. Besides, the elastic mechanical properties of tI6 and oF24 including bulk modulus, shear modulus, elastic modulus, and Poisson's ratio, are derived by means of both the general formula and the independent crystal system formula. The results show that the elastic modulus and tensile strength of tI6 and oF24 almost decrease linearly with increasing temperature. An increase of strain rate has little effect on the elastic modulus of tI6 and oF24, but it can result in an obvious increase of the tensile strength and ultimate strain. By calculating, tI6 possesses a stable tetragonal crystal structure and oF24 has a stable orthorhombic crystal structure, which are consistent with the previous results derived by the first-principle. The Young's modulus, shear modulus and Poisson's ratio display high anisotropy except for the bulk modulus. The anisotropic of oF24 is higher than that of tI6, while the stiffness and hardness of tI6 are greater than those of oF24. The present work can provide a theoretical reference for analyzing the mechanical properties of the approximate phase of decagonal quasicrystal as well as a novel numerical calculation method for determining the mechanical properties of related materials.