Electronic structure and phase stability study in the Ni-Ti system

We present the results of a phase stability study in the Ni-Ti system. In particular, the formation energies of the three Ni${\mathrm{Ti}}_2$, NiTi, and ${\mathrm{Ni}}_3$Ti compounds have been calculated using the full potential linear-muffin-tinorbital method. The correlation between the electronic concentration and the crystal structure is interpreted in terms of the filling of bonding states for the ${\mathrm{Ni}}_3$Ti compound. Two sets of effective cluster interactions are determined allowing us to include bcc- and fcc-based solid solutions in the phase stability analysis. Ordering effects are treated by means of the cluster variation method. An attempt to calculate the composition-temperature phase diagram of the Ni-Ti system is proposed.