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

TL;DR

This study uses first-principles calculations to analyze the finite temperature elastic properties of B2-AlRE intermetallics, providing insights into their thermal behavior and elastic anisotropy.

Contribution

It introduces a comprehensive first-principles approach combining phonon free energy and elastic constants for AlRE intermetallics at finite temperatures.

Findings

Elastic constants decrease with temperature

Excellent agreement with experimental data for Al

Elastic anisotropy varies with temperature

Abstract

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 is 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 = 0K, 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 has also been discussed.