First Principles Study on Elastic and Thermodynamic Properties of Mg1-xZnx Alloys

As one of the lightest metal materials in current industrial applications, Mg alloys are being widely used in automotive, aircraft, aerospace and biomedical industries because of their super high strength-to-weight ratio and biodegradability. However, their limited ductility and workability at room temperature have become a bottleneck for many applications. Therefore, it has become critically important to obtain the Mg alloys with improved strength and ductility. On the other hand, Zn is a transition metal element, often applied to improve the mechanical properties. Also it has basic safety for biomedical applications. So the Mg-Zn alloys have attracted considerable attentions in recent years. Extensively investigated experiments indicated that the hardness of Mg-Zn alloys increases with increasing Zn content. However, there are only a few reported works about their mechanical properties and theoretically thermodynamic properties of Mg-Zn alloys. In this work, first-principles investigations have been performed on lattice parameters, elastic properties and thermodynamic properties of hcp Mg and eight kinds of Mg1-xZnx alloys with different contents of Zn less than 2% (atomic fraction), using the virtual crystal approximation in the frame of the density functional theory and the density functional perturbation theory. The elastic constants of Mg and Mg1-xZnx alloys with different Zn contents have been investigated by using optimized lattice,