Grain boundary energy function for α iron

Polycrystalline alpha iron has been used in various applications, yet its microstructure design via grain boundary engineering (GBE) is not well established. One limiting factor is that while there are many different grain boundaries in the five-dimensional space of grain boundary types, relatively few of the energies have been determined. In this study, a piece-wise continuous grain boundary energy function for alpha iron is constructed to fill the entire five-dimensional space of grain boundary types using scaffolding subsets with lower dimensionality. Because the energies interpolated from the grain boundary energy function are consistent with the 408 boundaries that have been calculated using atomistic simulations, the energy function is then employed to generate a larger set of grain boundary energies. Comparisons between the interpolated energies and the measured grain boundary population indicate that they are inversely correlated for the high-energy anisotropy misorientations (those for which the difference between the maximum and minimum grain boundary energies is greater than 0.4 J/m(2)). The results suggest that GBE in the alpha iron should consider the high-energy anisotropy misorientations, rather than the twinning-related grain boundaries (Sigma 3, Sigma 9, Sigma 27a, and Sigma 27b) as in the case of fcc metals.

Automated summary

In this study, a piece-wise continuous grain boundary energy function was constructed for polycrystalline alpha iron to fill the entire five-dimensional space of grain boundary types. The results suggest that grain boundary engineering in alpha iron should consider high-energy anisotropy misorientations, rather than twin-related grain boundaries as in the case of fcc metals.