First-principles calculations on temperature- dependent elastic constants of rare-earth intermetallic compounds:YAg and YCu

TL;DR

This study uses first-principles calculations to predict how the elastic constants of YAg and YCu change with temperature, showing they become more ductile as temperature rises.

Contribution

It provides the first temperature-dependent elastic constants for YAg and YCu using a combined first-principles approach, validated against experimental data.

Findings

Elastic constants decrease with temperature from 0-1000K.

YAg and YCu remain structurally stable within this temperature range.

Ductility increases with rising temperature.

Abstract

we present the temperature-dependent elastic constants of two ductile rare-earth intermetallic compounds YAg and YCu with CsCl-type B2 structure by using a first-principles approach. The elastic moduli as a function of temperature are predicted from the combination of static volumedependent elastic constants obtained by the first-principles total-energy method with density functional theory and the thermal expansion obtained by the first-principles phonon calculations with density-functional perturbation theory. The comparison between our calculated results and the available experimental data for Ag and Cu provides good agreements. In the calculated temperature $0-1000K$, the elastic constants of YAg and YCu follow a normal behavior with temperature that those decrease with increasing temperature, and satisfy the stability conditions for B2 structures. The Cauchy pressure for YAg and YCu as a function of temperature is also discussed, and our results mean that YAg and YCu become more ductile while increasing temperature.