First-principles study of elastic properties of Cr-Al-N

TL;DR

This study uses first-principles DFT calculations to analyze how the elastic properties of Cr-Al-N alloys depend on composition, revealing trends consistent with experimental hardness and insights into their elastic and bonding behavior.

Contribution

It provides a detailed first-principles analysis of the elastic properties of Cr-Al-N alloys across compositions, highlighting compositional dependence and elastic isotropy at specific concentrations.

Findings

Young's and shear moduli increase with Al content

Bulk modulus remains nearly constant across compositions

Alloys exhibit brittle behavior with increasing Al content

Abstract

The elastic properties of paramagnetic cubic B1 (c-) Cr1-xAlxN ternary alloys are studied using stress-strain and energy-strain methods within the framework of Density Functional Theory (DFT). A strong compositional dependence of the elastic properties is predicted. Young's modulus, E, and shear modulus, G, exhibit the same compositional trends as experimentally measured hardness values (i.e. increasing with Al content), while bulk modulus, B, remains almost constant. The isotropic elastic response in the c-Cr1-xAlxN is predicted for concentrations around x=0.50. Brittle behavior and directional bonding characteristics are predominant in the c-Cr1-xAlxN coatings in the whole composition range, and become more pronounced with increasing Al content.