A Note on the Structure and Growth Mechanism of Spheroidal Graphite Crystals in Alloys Containing Carbon

Some considerations have been made on the structure and growth mechanism of spheroidal graphite crystals formed in Fe-C (cast iron), Ni-C, Co-C, Au-C, and Fe-C-Si alloys. It is proposed that grain boundaries in spheroidal graphite crystals are really very thin plate-like dendritic crystals with twinned structures, which grow at first, and that grains, which also have a twin relation with the boundary crystals, are formed subsequently among the said boundaries by the re-entrant corner mechanism. It is shown that the number of grains in a spheroidal graphite crystal and their branched structure observed experimentally can be interpreted by this model