Room-Temperature Mechanical Properties and Slow Crack Growth Behavior of Mg2Si Thermoelectric Materials

Mg2Si is of interest as a thermoelectric (TE) material in part due to its low materials cost, lack of toxic components, and low mass density. However, harvesting of waste heat subjects TE materials to a range of mechanical and thermal stresses. To understand and model the material's response to such stresses, the mechanical properties of the TE material must be known. The Mg2Si specimens included in this study were powder processed and then sintered via pulsed electrical current sintering. The elastic moduli (Young's modulus, shear modulus, and Poisson's ratio) were measured using resonant ultrasound spectroscopy, while the hardness and fracture toughness were examined using Vickers indentation. Also, the Vickers indentation crack lengths were measured as a function of time in room air to determine the susceptibility of Mg2Si to slow crack growth.