High coercivity Nd2(Fe,Co)14C-type ribbons prepared by melt spinning

Melt-spun Nd13Dy2Fe77-xCoxC6B2 (x = 0, 5, 10, 15, 20) ribbons with a high coercivity more than 2 T have been obtained. It was found that the ribbons quenched at the optimum wheel speed 15 m/s (as-spun ribbons) mainly consist of ferromagnetic 2: 14: 1 phase and paramagnetic NdC2 phase, and the ribbons spun at 25 m/s and subsequently annealed at 973 K for 15 min (as-annealed ribbons) are primarily composed of the magnetic 2: 14: 1 and 2: 17 phases. The magnetization process of as-spun ribbons controlled by a pinning of the domain wall is different from that of as-annealed ribbons determined by a nucleation of the reverse domain. This significant difference originates possibly from the existence of paramagnetic NdC2 phase acting as a pinning center in as-spun ribbons. In the as-annealed ribbons, the substitution of Co for Fe leads to increase of remanence (mu M-0(c)), maximum energy product ((BH)(max)) from 0.67 T, 9.7 MGOe for x = 0 to 0.84 T, 14.4 MGOe for x = 10, respectively. A coercivity of 2.74 T is obtained for as-quenched Nd13Dy2Fe77-xCoxC6B2 (x = 0) ribbons. (C) 2001 Elsevier Science B.V. All rights reserved.