Influence of Temperature and Orientation on Elastic, Mechanical, Thermophysical and Ultrasonic Properties of Platinum Group Metal Carbides

Abstract

The elastic, mechanical, thermophysical and ultrasonic properties of platinum group metal (PGM) carbides XC (X: Rh, Pd, Ir) have been investigated at room temperature. The Coulomb and Born-Mayer potential model has been used to compute second and third order elastic constants (SOECs and TOECs) at 0K and 300K. The obtained values of SOECs are used to evaluate the mechanical properties such as Young’s modulus, bulk modulus, shear modulus, Pugh’s indicator, Zener anisotropic constant and Poisson’s ratio at room temperature. The materials show the brittle nature as the value of Pugh’s indicator for PGM carbides has been achieved less than or nearly equal to 1.75. Again the values of SOECs are used to compute the ultrasonic velocities along <100>, <110> and <111> directions for the longitudinal and shear modes of wave propagation. Further the values of Debye temperature, thermal conductivity, specific heat per unit volume, energy density, average value of ultrasonic Grüneisen parameter, thermal relaxation time, non-linear parameter have been calculated with the help of SOECs, TOECs, ultrasonic velocities, density and molecular weight. Finally, the ultrasonic attenuation due to phonon-phonon interaction and due to thermoelastic relaxation mechanisms have been calculated with the use of all associated parameters. The calculated values of elastic, mechanical, thermophysical and ultrasonic properties are compared with available literature and discussed.