Nanocomposite Pr 2 Fe 1 4 B/α-Fe magnets have been synthesized by melt-spinning a Pr 8 Fe 8 6 B 6 alloy at low wheel speed in the range from 10 to 21.7m/s. Microstructural and magnetic studies showed that there is an optimum wheel speed (about 16.7m/s) at which a uniform Pr 2 Fe 1 4 B/α-Fe microstructure with fine α-Fe grains is developed directly from the melt. Lower speed gives larger grains for both the 2:14:1 and α-Fe, while higher speed leads to the appearance of an amorphous phase which will result in a Pr 2 Fe 1 4 B/α-Fe structure with larger α-Fe grains after a subsequent crystallization annealing. Magnetic properties obtained under the optimum-quenching followed by a subsequent annealing are M s =176.6emu/g, M r =118.2emu/g, M r /M s =0.67,H c =5.4kOe and (BH) m =12.6MGOe. The coercivity and energy product are about 20% higher than those obtained by over-quenching and then annealing due to the refinement of α-Fe size which leads to an enhanced exchange coupling between Pr 2 Fe 1 4 B and α-Fe. The fine α-Fe development is associated with its solidification behavior characterized by higher nucleation rate and lower growth rate during the rapid solidification.