The Electronic Structures, Elastic and Thermodynamic Properties of Alkali Earth Metal Doped Ni3ti Intermetallics

Abstract

The formation energy, electronic structure, elastic and thermodynamic properties of close–packed hexagonal Ni3Ti intermetallics doped with alkaline earth metals (Be, Mg, Ca, Sr, Ba) have been calculated by first principles method. The influences of pressure and strain on elastic properties are also investigated. It shows that the alkali earth metals tend to occupy the Ti sites preferentially. The formation energies of all the systems increase gradually with the doping concentration increasing. The calculated electronic properties show that the pseudo–energy gaps of the systems narrow down with the increase of doping atomic radius, indicating the proportion of covalent bond decreases gradually with atomic radius increase, resulting in the elastic strength weakened and the ductility enhanced. The Debye temperature and thermal conductivity also decrease with atomic radius increase. The elastic properties of Ni12Ti4-xMx (M= Be, Mg, Ca, Ba) systems are sensitive to strain index except Ni12Ti4-xSrx. The applied strain can restrain the elastic anisotropy to some extent.

Keywords: Ni3Ti intermetallics, Electronic structure, Elastic property, Doping