First-principles calculations on finite temperature elastic properties of B2-AlRE (RE = Y, Tb, Pr, Nd, Dy) intermetallics

We have investigated the finite temperature elastic properties of AlRE (RE = Y, Tb, Pr, Nd, Dy) with B2-type structures from first principles. The phonon free energy and thermal expansion are obtained from the quasiharmonic approach based on density-functional perturbation theory. The static volume-dependent elastic constants are obtained from energy–strain functions by using the first-principles total-energy method. The comparison between our predicted results and the ultrasonic experimental data for a benchmark material Al provides excellent agreements. At T = 0 K, our calculated values of lattice equilibrium volume and elastic moduli of our calculated AlRE (RE = Y, Tb, Pr, Nd, Dy) intermetallics agree well with the previous theoretical results. The temperature-dependent elastic constants exhibit a normal behavior with temperature, i.e., decrease and approach linearity at higher temperature and zero slope around zero temperature. Furthermore, the anisotropy ratio and sound velocities as a function of temperature have also been discussed.