The third-order elastic moduli and pressure derivatives for AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics with B2-structure: A first-principles study

TL;DR

This study uses first-principles calculations to determine third-order elastic moduli and pressure derivatives of AlRE intermetallics with B2 structure, highlighting the significance of third-order effects at finite strains.

Contribution

It provides the first-principles data on third-order elastic constants and pressure derivatives for a series of AlRE intermetallics, expanding understanding of their nonlinear elastic behavior.

Findings

Third-order elastic moduli are significant at strains over 3.5%.

Calculated elastic constants agree well with experimental and previous theoretical data.

Pressure derivatives are analyzed to understand pressure effects on these materials.

Abstract

The third-order elastic moduli and pressure derivatives of the second-order elastic constants of novel B2-type AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics are presented from first-principles calculations. The elastic moduli are obtained from the coefficients of the polynomials from the nonlinear least-squares fitting of the energy-strain functions. The calculated second-order elastic constants of AlRE intermetallics are consistent with the previous calculations. To judge that our computational accuracy is reasonable, the calculated third-order constants of Al are compared with the available experimental data and other theoretical results and found very good agreement. In comparison with the theory of the linear elasticity, the third-order effects are very important with the finite strains are lager than approximately 3.5%. Finally, the pressure derivative has been discussed.