Non-Linear Thermophysical Behaviour of Transition Metal Titanium

Abstract

The propagation of ultrasonic wave in the hexagonal closed packed (hcp) structured lanthanide metal titanium (Ti) has been investigated in temperature range 300-1000K. For this, initially the higher-order elastic constants (SOECs and TOECs) have been computed using Lennard–Jones interaction potential model. With the help of SOECs, other elastic moduli such as Young’s modulus (Y), bulk modulus (B), shear modulus (G), Poisson’s ratio (σ), and Pugh’s ratio (B/G) have been computed for Ti metal using Voigt–Reuss–Hill (VRH) approximation. Later on, orientation dependent three types of ultrasonic velocities including Debye average velocities have been evaluated utilizing calculated values of SOECs and density of Ti in the same temperature range. Thermophysical properties such as lattice thermal conductivity, thermal relaxation time, thermal energy density, specific heat at constant volume and acoustic coupling constant of Ti have been also evaluated at same physical conditions. The ultrasonic attenuation due to phonon-phonon interaction is most significant in chosen physical conditions. The ultrasonic properties have been correlated with thermophysical properties to understand the microstructural features and nature of the material.