Calculation of the atomic volumes of FeNi and FeCo alloys

The concentration dependence of the average atomic volume of f.c.c. and b.c.c. FeNi and FeCo alloys has been calculated at 300 K over the entire concentration range. The large deviations from linearity in these alloy systems are attributed solely to changes in the atomic magnetic moment μ of the Fe atoms. The volume V of an Fe atom depends on its moment μ through the relation V = V0 (μ = 0) + k μ2, where k is an atomic constant independent of the alloy structure and the environment of the Fe atom.