Temperature-dependent elastic properties ofα-beryllium from first principles

Abstract

Using density functional theory formulated within the framework of the exact muffin-tin orbitals method, we investigate the temperature dependence of the structural parameters and the elastic properties of the hexagonal closed-packed phase of Be $(\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Be})$. We find that the elastic constants follow a normal behavior with temperature: decrease with increasing temperature with a slightly increasing slope. Up to the melting point, the monocrystalline elastic constants decrease by an average of 16% and the polycrystalline elastic constants by 10%. These trends contradict the large temperature factor observed in high-temperature direct pulse ultrasonic experiments. At the same time, the low-temperature pulse echo measurements confirm the present theoretical findings. Our results call for further accurate experimental studies on the elastic properties of $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Be}$ at high temperatures.