Mechanical properties and work function of L21 structure AlCu2X (X=Ti, Mn, Zr, or Hf) intermetallics

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2012-05, Vol.545, p.13-19
• Main Authors: Dong, L.M., Han, Z.D., Guan, Y.Z., Li, W., Zhang, X.Y.
• Format: Article
• Language: English
• Subjects: Ab-initio calculations; Aluminides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Elasticity, elastic constants; Electron density of states and band structure of crystalline solids; Electron states; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Intermetallic compounds; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Miscellaneous; Physics; Surface double layers, schottky barriers, and work functions
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.02.066

► The ductility of AlCu2Zr is the largest among the intermetallics. ► Work function of (110) is higher than (100). ► Shear modulus and WF decrease with composition. First-principles calculations are performed to study on alloying stability, elastic properties, ductility and electronic properties of AlCu2X (X=Ti, Mn, Zr, or Hf) intermetallics within the generalized gradient approximation. The obtained lattice parameters for all intermetallics considered are very close to the corresponding experimental values. The calculated cohesive energy (Ecoh) and formation energy (ΔH) show that the AlCu2Zr crystal structure is more stable, and the alloying ability of AlCu2Zr is also stronger. The calculated density of states of these phases indicates that the highest structural stability of AlCu2Zr is attributed to the lower value of the DOS at the Fermi level, i.e., N(EF). The elastic constants Cij of these phases were calculated, and the bulk modulus B, shear modulus G were derived from the elastic constants. The calculations on the ratio of bulk modulus to shear modulus reveal that the ductility of AlCu2Zr is better than AlCu2Mn, AlCu2Ti and AlCu2Hf. In addition, the work functions (WF) and surface energies of (100) and (110) surfaces of AlCu2X intermetallics are also investigated. For the four AlCu2X intermetallics, the work function of (110) surface is higher than that of (100), and the surface with a higher work function is prone to have a lower surface energy. Furthermore, both shear modulus and WF decrease, and changes in both WF and bulk modulus of the four intermetallics have a similar trend, except for AlCu2Ti and AlCu2Hf. It is also revealed that with the increase of WF, the ductility decrease, which is attributed to a change in the nature of the atomic bonding or in the electronic structure induced by the alloying.