First-Principles Study of the Structural, Mechanical, Electronic, and Thermodynamic Properties of AlCuM (M = Ti, Cr, Zr, Sc, Hf, Mn, Pa, Lu, Pm) Ternary Intermetallic Compounds.

Based on the first principles, the structural stability, mechanical characteristics, electronic structure, and thermodynamic properties of AlCuM (M = Ti, Cr, Zr, Sc, Hf, Mn, Pa, Lu, Pm) are investigated. The calculated results indicate that the AlCuPa crystal structure is more stable and that AlCuPa should be easier to form. All of the AlCuM 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 AlCuM compounds. It is demonstrated that all computed AlCuM compounds are ductile and mechanically stable, with AlCuHf having the highest bulk modulus and AlCuMn having the highest Young's modulus. AlCuMn has the highest intrinsic hardness among AlCuM compounds, according to calculations of their intrinsic hardness. The electronic densities of states are discussed in detail; it was discovered that all AlCuM compounds form Al-Cu and Al-M covalent bonds. Additionally, we observe that the Debye temperature and minimum thermal conductivity of AlCuMn and AlCuSc are both larger than those of others, indicating stronger chemical bonds and higher thermal conductivities, which is consistent with the elastic modulus results.