The grain diffused from the molten bath at eutectic composition and eutectic temperature.
For example, from the solidifying austenite-graphite eutectic of cast iron, the eutectic grain is diffused from a crystal nucleus through this process and continues growing in the form of spheres.
The diffused graphite in the eutectic grain branches off in the shape of a more or less dendritic structure. Figure 1 illustrates eutectic grains in flake graphite cast iron that are made visible by means of etching.
Eutectic grain count