Phase selection in undercooled Fe–Nd alloy melts

Undercooling experiments on Fe89.5Nd10.5, Fe87.5Nd12.5 and Fe75Nd25 alloy melts have been performed by electromagnetic levitation and drop tube experiments. Phase formation in Fe–Nd alloys is of interest due to the ternary compound Fe14Nd2B1, which exhibits extraordinary hard magnetic properties. Under equilibrium solidification conditions, melts of the investigated composition range solidify primarily in the γ-Fe solid solution, which is followed by the peritectic formation of the chemically ordered Fe17Nd2-phase. In electromagnetic levitated Fe75Nd25 alloys the primary crystallisation of γ-Fe could be suppressed in favour of the peritectic phase with rising undercooling. In Fe-rich alloys the direct crystallisation of the Fe17Nd2-phase was only observed in drop tube solidified particles with diameters below 0.2 mm.