The effects of Zr and Co substitutions for Fe on the magnetic properties of nanocrystalline near-stoichiometric (Nd{sub}0.75Pr{sub}0.25){sub}12(Fe{sub}{sub}(1-x)Co{sub}x){sub}(82-z)Zr{sub}zB{sub}6 (x = 0, 0.1, 0.2 and z = 0-4) alloy ribbons are reported. The nanoscale structures were derived by devitrification annealing of amorphous as-cast ribbon. Very good combinations of energy product, (BH){sub}(max)(～160 kJ/m{sup}3) and intrinsic coercivities, i{sub left}H{sub}c (within the range 800-1400 kA/m for various Zr concentrations) were achieved for the Co-free alloys although the Zr addition resulted in some reduction in T{sub}c. For alloys in which, also, 10 and 20 of the Fe was substituted by Co, excellent remanence enhancement, J{sub}r (to >1 T) were achieved with 1 at Zr addition. Combined with excellent squareness of the J-H second quadrant, this gave (BH){sub}(max) up to 175 kJ/m{sup}3, together with Curie temperatures, T{sub}c of >375 ℃ and >460 ℃ for 10 and 20 Co, respectively, and with only minor reductions in i{sub left}H{sub}c. The role of Zr in promoting uniform and refined grain structures and enhancing the magnetic properties will be discussed.
展开▼
