Melt-spun Nd13Dy2Fe77-xCoxC6B2 (x = 0, 5, 10, 15, 20) ribbons with a high c
oercivity more than 2 T have been obtained. It was found that the ribbons q
uenched 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 ribbon
s 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 th
e domain wall is different from that of as-annealed ribbons determined by a
nucleation of the reverse domain. This significant difference originates p
ossibly from the existence of paramagnetic NdC2 phase acting as a pinning c
enter in as-spun ribbons. In the as-annealed ribbons, the substitution of C
o 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 = 1
0, respectively. A coercivity of 2.74 T is obtained for as-quenched Nd13Dy2
Fe77-xCoxC6B2 (x = 0) ribbons. (C) 2001 Elsevier Science B.V. All rights re
served.