The microstructure evolution and the recrystallization of undercooled Ni-1at%Fe alloy were investigated by employing the glass fluxing technique in combination with cyclical superheating. The experiments of rapid quenching and naturally cooling on Ni-1at%Fe alloy after recalescence were conducted. It is proved that the fine structure is the product of recrystallization under high undercooling. The evolution of microstructure was systematically investigated by applying the calculation of dimensionless superheating. Two grain refinements were detected. The first grain refinement occurs owing to the dendrite break-up or ripening induced by remelting. The second grain refinement occurs due to the recrystallization induced by stress cumulation.