Structural, mechanical and thermodynamic properties of Mg₂₄RE₅: A first-principles investigation

Magnesium (Mg) alloys, especially high-modulus Mg alloys, are catching more and more attention for their excellent performance. Doping rare earth elements (RE) and then generating hard intermetallic is one of the popular ways to strengthen the Mg alloys. As an important intermetallic, Mg₂₄RE₅ is rarely investigated. In this work, we comprehensively investigate the structural, mechanical, and thermodynamic properties of Mg₂₄RE₅ by first-principles calculations. The accuracy of our results is confirmed by comparing with limited previous results. All Mg₂₄RE₅ are energy-stable, mechanically stable, and dynamically stable. The lattice constant is almost linear with the ionic radii of the corresponding RE elements. Mg₂₄Y₅ shows the largest Young's modulus (54.6 GPa), followed by Mg₂₄Lu₅ and Mg₂₄Tm₅, while Mg₂₄Sm₅ and Mg₂₄Gd₅ show the lowest anisotropy. Moreover, we calculated the thermodynamic properties for all Mg₂₄RE₅ and obtained the critical temperature for heat capacity. All in all, this work provides plentiful fundamental data for designing RE-containing Mg alloys.