Nanocomposite Nd-Fe-B type magnets

The temperature dependences of magnetic properties for nanocomposite two-phase Nd12.6Fe69.8 - xCo11.6ZrxB6 /alpha-Fe (x = 0 and 0.5) hot pressed magnets, with an excess of alpha-Fe (10, 20, 37.5 and 50 vol.%), have been studied. These materials have been prepared by high-energy ball-milling and annealing. For example, hot pressing at 830 degrees C of Nd12.6Fe69.3Co11.6Zr0.5B6/alpha-Fe, containing 37.5 vol.% alpha-Fe, resulted in isotropic magnets with J(r) = 0.95 T, H-J(c) = 427 kA m(-1) and p similar to 7.59 g cm(-3). The temperature coefficients (from 20 to 140 degrees C) of remanence alpha(J(r)) and coercivity beta(H-J(c)) of this magnet are: -0.07% degrees C-1, -0.35% degrees C-1, which are smaller than that of sintered Nd-Fe-B magnets. (C) 2000 Elsevier Science S.A. All rights reserved.