A theoretical study of the stability, mechanical and thermal properties of AlNiCuCo equimolar high entropy alloy

Abstract

The stability, elastic and thermal properties of random AlNiCuCo high entropy alloy solid solution with two different crystal structures are investigated by special quasi-random structure (SQS) method based on Ab-initio calculations and 'Ab-initio molecular dynamics (AIMD) simulations. The calculated formation energy and elastic constants suggest that body centered cubic structure is more stable for the alloy, which agree well with the empirical criterions based on previous experimental studies. Based on the stable structure, the ideal tensile tests are carried out and the polycrystalline elastic modulus is estimated. The ideal tensile strength confirms the credibility of the computed elastic constants based on generalized Hooke's low. On the other hand, the calculated polycrystalline elastic modulus indicates the brittleness of the alloy. Furthermore, the thermal properties, such as thermal expansion coefficient and constant volume heat capacity, as a function of temperature are obtained using quasi-harmonic Debye-Grüneisen model.