Significant elastic anisotropy in Ti$_{1-x}$Al$_x$N alloys

TL;DR

This study reveals that Ti$_{1-x}$Al$_x$N alloys exhibit significant elastic anisotropy and compositional-dependent elastic properties, which are crucial for understanding their mechanical behavior and phase transformations.

Contribution

It provides a detailed analysis of how Al-content influences elastic anisotropy and bond strength in Ti$_{1-x}$Al$_x$N alloys, combining theoretical and experimental insights.

Findings

Elastic constant C11 varies by over 50% with Al-content.

Increasing Al-content weakens average bond strength.

Higher Al-content leads to greater elastic anisotropy.

Abstract

Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti$_{1-x}$Al$_x$ N alloys. The elastic constant, C$_{11}$, changes by more than 50% depending on the Al-content. Increasing the Al-content weakens the average bond strength in the local octahedral arrangements resulting in a more compliant material. On the other hand, it enhances the directional (covalent) nature of the nearest neighbor bonds that results in greater elastic anisotropy and higher sound velocities. The strong dependence of the elastic properties on the Al-content offers new insight into the detailed understanding of the spinodal decomposition and age hardening in Ti$_{1-x}$Al$_x$N alloys.