Single-phase lightweight high-entropy alloys with enhanced mechanical properties

To develop single-phase lightweight high-entropy alloys (LWHEAs), we perform massive screening over a vast material space containing more than 560,000 possible compounds by employing thermodynamic principles and examine the mechanical properties of the resulting alloys based on density functional theory (DFT) calculations. Considering LWHEAs composed of five principal elements including light atoms such as Li, Mg and Al, we identify 40 optimal atomic compositions for single-phase solid solutions in body-centered-cubic structure. Combined with DFT calculations, it is demonstrated that the valence electron concentration plays an important role in determining elastic moduli and that the identified LWHEAs are ductile as is evidenced by the satisfied Pugh criteria and positive Cauchy pressure. In cases of shear modulus and yield strength, pd-hybridization between Al and transition metal atoms is shown to make a significant contribution through forming strong directional bonds. Together with an observation that the inclusion of Li and Mg atoms is instrumental in reducing the overall density, the present results provide a valuable guidance to develop novel, low-density high-entropy alloys.