Abstract
A recent generalised perturbation method starting from the completely disordered state is used for the computation of interaction potentials responsible for ordering effects in ferromagnetic Fe alloys. It is found that the 'effective' pair potential at the first neighbour position varies with the impurity concentration and even changes its sign in FeCr. A comparison with experimental data is tentatively made and discussed, in spite of the lack of experimental data at sufficiently low quenched state temperatures.