The effect of Co on the enhanced magnetic properties of Fe3B/Nd2Fe14B magnets

The addition of Co into Nd4Fe77.5-xCox(HfGa)(y) B-18.5 (0 less than or equa l to x less than or equal to 5, y = 0, 0.5) was found to enhance the magnet ic properties of Fe-3 B/Nd-2 Fe14B nanocomposite magnets. The enhancement r esulted from the fact that Co retarded the crystallization of alpha-Fe or F e3B but accelerated that of Nd2Fe14B. The decreased interval between the on set of crystallization temperature of Fe3B and Nd2Fe14B phases enabled the grain growth of each phase to be uniform during a post-annealing of the mel t-spun ribbons. The addition of 3-5 at% Co into ternary composition Nd4Fe77 .5B18.5 increased the coercivity (H-i (c)) from 3.27 to 3.54 kOe with the e nhanced remanence value (4 pi M-r) around 11.54 kG. From the ribbon magnets of Nd4Fe71.5Co5Hf0.5Ga0.5B18.5 made at 16 mis and annealed at 680 degrees C for 10 min, the magnetic properties of B-r = 11.54 kG, H-i(c) = 3.54 kOe, and (BH)(max) = 14.35 MGOe were obtained from volume production line. (C) 2000 Elsevier Science B.V. All rights reserved.