First-Principles Study of the Structural, Mechanical, Electronic, and Thermodynamic Properties of AlCu[sub.2]M Ternary Intermetallic Compounds

Based on the first principles, the structural stability, mechanical characteristics, electronic structure, and thermodynamic properties of AlCu[sub.2]M (M = Ti, Cr, Zr, Sc, Hf, Mn, Pa, Lu, Pm) are investigated. The calculated results indicate that the AlCu[sub.2]Pa crystal structure is more stable and that AlCu[sub.2]Pa should be easier to form. All of the AlCu[sub.2]M compounds have structural stability in the ground state. Elastic constants are used to characterize the mechanical stability and elastic modulus, while the B/G values and Poisson ratio demonstrate the brittleness and ductility of AlCu[sub.2]M compounds. It is demonstrated that all computed AlCu[sub.2]M compounds are ductile and mechanically stable, with AlCu[sub.2]Hf having the highest bulk modulus and AlCu[sub.2]Mn having the highest Young’s modulus. AlCu[sub.2]Mn has the highest intrinsic hardness among AlCu[sub.2]M compounds, according to calculations of their intrinsic hardness. The electronic densities of states are discussed in detail; it was discovered that all AlCu[sub.2]M compounds form Al-Cu and Al-M covalent bonds. Additionally, we observe that the Debye temperature and minimum thermal conductivity of AlCu[sub.2]Mn and AlCu[sub.2]Sc are both larger than those of others, indicating stronger chemical bonds and higher thermal conductivities, which is consistent with the elastic modulus results.