In the case of aluminium alloys, a postcasting homogenisation heat treatment is applied in order to improve extrudability. During this homogenisation, a phase transformation occurs and the intermetallic structure evolves from an interconnected network of plate-like structures into a more discrete distribution of particles. The morphology of these intermetallics has been the subject of many studies employing conventional 2D characterisation. However, recently, it has been shown that 2D analyses can be misleading and that techniques suitable for quantification of 3D structures can provide more reliable information.

In this study, serial sectioning and 3D reconstruction techniques were used to reveal the three-dimensional morphology, connectivity and distribution of the intermetallic microstructure, and the evolution of these parameters during homogenisation. The qualitative and quantitative analysis of the reconstructed intermetallic microstructures, with particular reference to the determination of the spatial distribution of the absolute, mean and Gaussian curvature is discussed.