Ordering phenomena and modelling of pair interactions in Ni3Ga compound

In the present investigation, we have chosen Ni3Ga as a model L12 compound to study (1) the equilibrium degree of order at various temperatures and (2) the kinetics of ordering and disordering. In this paper we report the method of estimating the long-range order parameter from the resistivity data and how to derive the effective pair interaction (EPI) energy. It is then compared with those evaluated from thermodynamic activity measurements and also with those converted from Compound Energy Formalism (CEF) and CALPHAD modelling. Such adequately evaluated EPI energy values can be conveniently employed for calculating point defect concentrations at various temperatures and compositions using common statistical-thermodynamic methods, as a Bragg-Williams model.