Three-dimensional visualization and quantitative characterization of grains in polycrystalline iron

Serial sectioning is employed to reconstruct the three-dimensional microstructure of polycrystalline iron for visualization and characterization of the three-dimensional geometry of α-iron grains. Full three-dimensional morphology of 1386 α-iron grains is investigated and compared with different theories with a particular emphasis on the investigation of the nearest neighbor grain effects in real three-dimensional polycrystalline systems. Different metric and topological parameters of three-dimensional grains are determined and their distributions and correlations are studied. Some important relationships between different parameters of grains are practically demonstrated by using visualization techniques for the first time. The results of certain distributions and parameter correlations revealed that, the non-random nearest-neighbor grain effects in polycrystalline systems are very important and play a vital role in the evolution of microstructure. By considering the effects of nearest-neighbor grains, the relationship between grain size and grain topology is studied and found an excellent linear relationship between these parameters, which verifies the validity of a recently proposed grain topology–size equation (Luan et al. EPL 99, 28001 (2012)). Whereas, the grain topology–size relationship investigated by neglecting the nearest-neighbor effects is represented by a curve concave downwards. Furthermore, the relationship between grain edge length and grain face number is also investigated by taking into account the nearest-neighbor effects and obtained a good linear relationship; while, these parameters are correlated by a curve slightly convex downwards when the relationship is studied by considering the grains in a mean field.