An externally applied magnetic field during heat treating the Nd₂Fe₁₄B/Fe₃B based spring magnet was found to enhance the exchange coupling between the hard and soft magnetic grains. More than 30% increase in M_r/M_s values for melt-spun Nd₄Fe_73.5Co₃(Hf_1-xGa_x)B_18.5(x=0, 0.5, 1) alloys was resulted from a uniform distribution of Fe3B, α-Fe and Nd₂Fe₁₄B phases, and also from a reduced grain size of those phases by 20%. The externally applied magnetic field induced a uniform distribution of fine grains. A study of Mossbauer effect also report that the enhancement of total magnetization of nanocomposite Nd₂Fe₁₄B/Fe₃B alloys is attributed to an increased formation of Fe₃B after magnetic annealing.