Atomistic simulations of the interaction of alloying elements with grain boundaries in Mg

Quantum density functional theory (DFT) is used to compute binding energies of important alloying elements (Ag, Zn, Ti, Al, Cd, Zr, Y, Ca, Nd, Ce and La) to a Σ7 grain boundary (GB) in Mg. In particular, quantifying the interaction of rare earth (RE) elements with Mg GBs is of significance given the strong effect of these solutes on modifying the texture of Mg alloys. For most alloying elements studied, the binding energy scales with the size of the solute and the local GB site volumes. Based on these trends, a model for the solute-GB binding energy is developed which accurately captures the behavior of the technologically important RE solutes and Ca. This model is then employed in conjunction with molecular statics calculations to predict solute segregation to general GBs not accessible by DFT. The predicted trends are found to be in qualitative agreement with available experimental data for GB segregation in Mg.