Electronic structure and physical properties of hcp Ti3Al type alloys

Abstract According to the basic information of sequences of Ti and Al characteristic atoms in hep Ti-Al system, the compositional variations of the electronic structure, atomic potential energies, atomic volumes, lattice constants and cohesive energies of the ordered hcp Ti 3 Al type alloys were calculated by the framework of systematic science of alloys(SSA). The electronic structure of the hcp Ti 3 Al compound consisted of Ψ Ti 4h and Ψ Al Oh atoms is 0.75[Ar] (3 d n ) 0.573 (3 d c )2.1685(4 S c 0.972 (4 S f ) 0.3093 +0.25[Ne](3 s c ) 1.32 , (3 p c ) 1.19 (3 Sf ) 0.49 . The factors of controlling lattice stability are electronic structure, atomic energies and atomic concentration. The Ψ Ti 4h atoms play a determinative role in forming D0 19 structure with a =0.287 2 nm, c =0.456 4 nm, atomic cohesive energy ɛ=4.810 8 eV/atom and heat of formation Δ H =-0.332 8 eV/atom. These calculated values are in good agreement with experimental values ( a =0.287 5 nm, c =0.46 0 nm, Δ H =-0.27, -0.29 eV/atom). The calculated cohesive energy of the hep Ti 3 Al compound is slightly bigger than that of the fcc Ti 3 Al. This is a good sign that makes it feasible to stabilized L1 2 structure of the hcp Ti 3 Al compound by ternary element. The new element should have more d c -electrons than Ti-metal and occupy at the Ti-lattice points.