Elastic constants and thermophysical properties of Al-Mg-Si alloys from first-principles calculations

Abstract

The lattice constants and elastic constants for Al-Mg-Si alloys have been calculated by using first-principles total energy calculations within the generalized gradient approximation. The calculated results are in good agreement with available experimental and theoretical results. The polycrystalline shear modulus, Young's modulus and Poisson's ratio are also estimated from the calculated single crystalline elastic constants. The Young's modulus and shear modulus increase following the precipitation sequence in Al-Mg-Si. The Debye sound velocity, Debye temperature, Grüneisen constant, heat capacity and linear coefficients of thermal expansion are predicted for the considered Al-Mg-Si alloys based on the Debye-Grüneisen model. The calculated values of Mg2Si agree well with the previous experimental and theoretical results. © Carl Hanser Verlag GmbH & Co. KG.