Quantifying the differences in properties between polycrystals containing planar and curved grain boundaries

Abstract

There are several methods in which grain boundaries can be made for modelling, but most produce planar (flat) grains. In this study, we investigated the difference in materials properties between polycrystalline systems comprised of planar grain and curved grain boundaries. Several structural and mechanical properties for both systems were determined. For systems with curved grain boundaries, it was found that the elastic moduli are all larger in magnitude, the excess volumes are comparable, and the plastic properties are smaller. In addition, a grain tracking algorithm was used to determine the differences in the numbers of triple junctions detected between polycrystalline systems with planar and curved grain boundaries. This can be theoretically determined and compared to a simple model system. We find that planar systems of grain boundaries possess significantly more triple junctions than systems of curved grain boundaries by a factor of two. There are also systematic differences between the two types of a system when they undergo grain growth, when there is an anomalous close-packed hexagonal phase which grows in the system of planar grain boundaries.