New interatomic potential for Mg-Al-Zn alloys with specific application to dilute Mg-based alloys

Because of its very large c/a ratio, zinc has proven to be a difficult element to model using semi-empirical classical potentials. It has been shown, in particular, that for the modified embedded atom method (MEAM), a potential cannot simultaneously have an hcp ground state and c/a ratio greater than ideal. As an alloying element, however, useful zinc potentials can be generated by relaxing the condition that hcp be the lowest energy structure. In this paper, we present a MEAM zinc potential, which gives accurate material properties for the pure state, as well as a MEAM ternary potential for the Mg-Al-Zn system which will allow the atomistic modeling of a wide class of alloys containing zinc. The effects of zinc in simple Mg-Zn for this potential is demonstrated and these results verify the accuracy for the new potential in these systems.