Elastic and thermodynamic properties of B2-MgX intermetallics: A high throughput first-principles investigation

Abstract

Precipitation strengthening is an effective approach in Mg alloys, and hence, it is worthwhile investigating the properties of the Mg-containing intermetallics. In the present work, the thermodynamic and mechanical properties of B2-MgXs (69 different elements) are calculated by high-throughput first-principles calculations. The static properties, including equilibrium volume, equilibrium energy, and bulk modulus, and thermodynamic properties, including linear thermal expansion coefficient (LTEC), are predicted. Meanwhile, the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) are calculated using an efficient strain-stress method. The consistency between our results and the limited experimental or previous theoretic work confirms the high reliability of the present work. Using SOECs and equilibrium energy, the stability of MgXs is assessed from mechanics, energy and lattice dynamics, and 33 (out of 69) stable compounds are screened out. According to Young's and shear modulus, the MgXs are divided into four classes, and the first two classes present high modulus, high ductility, and reasonable anisotropy, equipping those compounds as promising candidates for precipitation strengthening in Mg alloys. In addition, the pressure and temperature dependence of SOECs is estimated using TOECs and LTEC. Furthermore, the present work provides abundant fundamental data for the design of new Mg alloys.