Structural and elastic properties under pressure effect of Hf₂AlN and Hf₂AlC

Abstract

The structural and elastic properties under pressure effect of Hf₂AlC and Hf₂AlN have been studied using the pseudo-potential plane-waves method based on density functional theory. Lattice parameters and their pressure dependence as well as elastic constants and their pressure dependence were calculated. We derived the bulk and shear moduli, Young's modulus and Poisson's ratio for ideal polycrystalline Hf₂AlX aggregates. We estimated the Debye temperature of Hf₂AlX from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of Hf₂AlC and Hf₂AlN compounds, and it still awaits experimental confirmation.

Keywords:

• MAX phases
• ab initio
• structural properties
• elastic properties
• pressure effect

Acknowledgements

The author would like to express his sincere gratitude to Dr Claude Demangeat and Dr Cyril Bourgogne from Institut de Physique et Chimie des Matériaux de Strasbourg-France, for their hospitality and computing facilities.