Within the range of undercooling of the Fe–30Co alloy examined here, the alloy goes through two grain refinement processes and one grain coarsening process. The first grain refinement takes place in the lower undercooling range, ΔT = 22–87 K; whereas the second occurs at an undercooling of about 183 K; both of these grain refinements result from the remelting of the originally formed dendritic structure. The grain coarsening process takes place when a critical value of undercooling, ΔT = 203 K, is exceeded and is the result of an effort to reduce the high grain boundary interfacial energy associated with the existence of a high density of metastable phase dendrite cores.