Structural Stability, Mechanical, and Electronic Properties of Al5TM (TM = Mo, Nb, Os, Re, Ru, Ta, Tc, Ti) Intermetallics

Al-based intermetallic compounds possess excellent mechanical and thermal properties, making them promising candidates for high-temperature structural applications. In this study, the structural stability, mechanical properties, and electronic characteristics of Al₅TM (TM = Mo, Nb, Os, Re, Ru, Ta, Tc, Ti) intermetallic compounds were systematically investigated using first-principles calculations based on density functional theory. All alloys exhibit negative formation energy, indicating favorable thermodynamic stability. Elastic constant analysis shows that all compounds satisfy the Born stability criteria, confirming their mechanical stability. Among them, Al₅Mo (205.9 GPa), Al₅Nb (201.1 GPa), and Al₅Ta (204.1 GPa) exhibit relatively high Young's moduli, while Al₅Os, Al₅Re, and Al₅Ru demonstrate large bulk moduli and good ductility. The high Debye temperatures of Al₅Mo (600.5 K) and Al₅Nb (606.7 K) suggest excellent thermal stability at elevated temperatures. Electronic structure analysis reveals that all alloys exhibit metallic behavior with no band gap near the Fermi level. The hybridization between TM-<i>d</i> and Al-3<i>p</i> orbitals enhances the covalent bonding between Al and TM atoms. This study provides theoretical guidance for the design and application of high-performance Al-based intermetallic compounds.