Growth kinetics and precipitation phenomena in undercooled Nd–Fe–B melts with Ti and C additions

Abstract The microstructure and the solidification kinetics of stoichiometric Nd–Fe–B alloy with Ti and C additions were investigated using the electromagnetic levitation technique. In situ temperature–time characteristics were carried out. A strong reduction of the growth velocity of the Nd 2 Fe 14 B phase was observed in the Nd–Fe–B–Ti–C alloy compared to the addition-less Nd–Fe–B alloy. The undercoolability of the melt depends on the alloy composition. Moreover, at high TiC contents, the maximum undercooling level is strongly reduced turning to low cooling rates. The TiC solution and its formation were studied in overheated and undercooled samples, respectively after subsequent quenching. The cooling rate prior to solidification influences drastically the morphology of the TiC precipitates which affects strongly the nucleation of the properitectic γ -Fe phase in the undercooled stage.