A description of the effect of short-range ordering in BCC phases with four sublattices

The effect of short range ordering (SRO) on the Gibbs energy is discussed for the BCC phases within the framework of compound energy formalism (CEF). Although in the compound energy formalism, SRO is not explicitly described it is possible to include the contribution through the reciprocal parameter. Introducing the reciprocal parameter of the form L i , j : i , j : ⁎ : ⁎ for the four sublattice models, one can describe the contribution of SRO to the Gibbs energy in the CEF. Compared to the results from the MC simulations, the present estimate of the SRO, based on the CEF, provided reasonable agreement for SRO, although the CEF gives a slightly higher transition temperature. By introducing the positive value of the 3nn interaction parameter, the order of the transition is of the first order. This result suggests that for the assessment of the phase diagrams where the D03/B2 phase boundaries are well separated, the 3nn pair interaction parameter has to be considered.