Effect of Alloying Elements on the α- γ Phase Transformation in Iron

Small concentrations of alloying elements can modify the α - γ phase transition temperature T c of Fe. We study this effect using an atomistic model based on a set of many-body interaction potentials for iron and several alloying elements. Free-energy calculations based on perturbation theory allow us to determine the change in T c introduced by the alloying element. The resulting changes are in semi-quantitative agreement with experiment. The effect is traced back to the shape of the pair potential describing the interaction between the Fe and the alloying atom.