  Al-Si alloys processed by laser rapid solidification yield eutectic
microstructures with ultrafine and interconnected fibers. Such fibrous
structures have long been thought to bear resemblance to those formed in
impurity-doped alloys upon conventional casting. Here, we show that any
similarity is purely superficial. By harnessing high-throughput
characterization and computer vision techniques, we perform a three-dimensional
analysis of the branching behavior of the ultrafine eutectic and compare it
against an impurity-modified eutectic as well as a random fractal (as a
benchmark). Differences in the branching statistics point to different
microstructural origins of the impurity- and quench-modified eutectic. Our
quantitative approach is not limited to the data presented here but can be used
to extract abstract information from other volumetric datasets, without
customization.
