First-principles calculation for mechanical properties of TiZrHfNbTa series refractory high-entropy alloys

Refractory high-entropy alloys (RHEAs) are considered crucial candidates to replace traditional hightemperature alloys due to their outstanding mechanical properties. Investigating the relationship between their composition and mechanical properties is important for advancing their application. This study examines the influence of varying elemental composition on the mechanical properties of the TiZrHfNbTa series RHEAs, known for their excellent toughness, using first-principles calculation combined with the virtual crystal approximation method. Calculations of physical parameters such as lattice constants, elastic modulus, hardness, yield strength, and dislocation energy factor indicate that adding elements with larger atomic radius and densities increases the lattice constants and density of the alloys. Adding more VB subgroup elements improves the elastic modulus, hardness, and strength of the alloy, with the TiHfNbTa alloy exhibiting the highest yield strength, approximately 1.28 GPa. The addition of the strongly metallic element Hf significantly enhances the Poisson's ratio and dislocation nucleation ability of the alloy, and its atomic bonds exhibit metallic bonding, which contributes to the improvement of the toughness of the alloy. This study provides an effective theoretical prediction for further investigation of the mechanical properties of the TiZrHfNbTa series RHEAs.