Room and high temperature mechanical properties of Mg2Si, Mg2Sn and their solid solutions

Knowledge of the mechanical properties of thermoelectric materials at high temperature is required for the modelling and optimization of a thermoelectric generator under application conditions. We present room and high temperature characterization of Young's modulus for Mg2Si, Mg2Sn and their solid solutions establishing a linear dependence, both on composition and on temperature. Through the comparison of Resonant Ultrasound Spectroscopy and free vibration techniques, we measure the elastic moduli with high precision. The comparison of our results (E = 110 GPa for Mg2Si and 78 GPa for Mg2Sn) to first principles calculations and experimentally reported data shows good agreement. Additionally, by estimating the Poisson ratio, we calculate the temperature-dependent shear modulus G and finally provide a simple bilinear function for Young's and shear moduli as a function of temperature and composition. (C) 2020 Elsevier B.V. All rights reserved.