Investigating the elastic, mechanical, and thermal properties of polycrystalline Mo2C under high pressure and high temperature

Understanding pressure-induced acoustic velocity-elasticity behavior has extraordinary significance in the fields of materials science and earth science. Herein, we used an advanced high-pressure high-temperature (HPHT) method to synthesize pure-phase beta-Mo2C bulk ceramics. The sound velocity-elasticity behavior, thermodynamic properties, and mechanical behavior of the synthesized beta-Mo2C ceramics were systematically investigated by insitu high-pressure ultrasonic interferometry and theoretical calculations. The compressive and shear wave velocities, isothermal bulk modulus, shear modulus, Vickers hardness, fracture toughness, Debye temperature, and melting temperature of polycrystalline beta-Mo2C exhibited a monotonic increase with increasing pressure. The experimental and calculation results showed that beta-Mo2C had strong ductile behavior and was a ductile ceramic. Additionally, the temperature-hardness relationship of the as-synthesized polycrystalline beta-Mo2C was investigated by in-situ high-temperature Vickers indentation measurements. The hardness of beta-Mo2C gradually decreased with increasing temperature, and this ceramic still maintained a hardness as high as 12.3 GPa at 500 degrees C. These results suggest that the intrinsic mechanical and thermodynamic properties of beta-Mo2C are dominated by its unique electronic structure and bonding mode.