Interaction energy between transition impurities and stacking faults of compact transition metals

Abstract

The interaction energies between isolated transition impurities and stacking faults in compact transition metals have been calculated using a tight-binding description of the d-band and a moment expansion of the density of states. They are short range, i.e. not negligible only when the impurity is located in the proper error planes and the adjacent ones. With respect to the matrix d-filling, the interaction energies have an oscillatory behaviour, they are nearly proportional to the valence difference, and they are connected with the difference of dissolution energy in f.c.c. and h.c.p. lattices. For a valence difference of about 1, they reach the contribution of a metal atom to the stacking fault energy (∼ 10⁻² eV) of the pure metal, suggesting Suzuki's segregations. The interaction energies are not proportional to the number of stacking errors but are related to them in another way. Finally, a more basic understanding of the alloying effect on stacking fault energy is given in terms of impurities favouring f.c.c. or h.c.p. lattices.