Accurate prediction of high-temperature elastic constants of Ti0.5Al0.5N random alloy

Using highly accurate ab initio molecular dynamic simulations we calculate elastic constants of Ti0.5Al0.5N as a function of temperature up to 1500 K and compare the results with those obtained for TiN. We analyze the variation of the material's elastic anisotropy with temperature by calculating directional Young's moduli and Poisson ratios on the (100), (110) and (111) crystallographic planes. We show that though the elastic moduli of Ti0.5Al0.5N strongly decrease upon heating, the elastic anisotropy increases with temperature unlike in TiN. Since several approximate approaches have recently been utilized to predict elastic constants of Ti0.5Al0.5N at elevated temperature we compare our results with published data and benchmark the different approximate schemes. Giving the fact that Ti(1-x)AlxN is a prototypical system for hard coating applications, we conclude that the recently developed symmetry imposed force constants approach combined with the temperature dependent effective potential method is accurate and computationally cost-effective for this material class.

Automated summary

Using ab initio molecular dynamics simulations, the elastic properties of Ti0.5Al0.5N at high temperatures were studied, showing an increase in elastic anisotropy with temperature. Comparisons with TiN were made, and it was suggested that the symmetry imposed force constants approach combined with the temperature-dependent effective potential method is accurate for the hard coating material class Ti(1-x)AlxN.