Magnetically soft nanocrystalline powders of Fe73.5Cu1Nb3Si13.5B9 obtained-by mechanical alloying and ball milling

Magnetically, soft nanocrystalline powders of Finemet alloy (Fe73.5Cu1Nb3Si13.5B9) were produced applying three techniques: (i) mechanical alloying of elemental powder mixtures, (ii) ball milling of crystalline ingots produced by induction melting of constituent elements of the alloy and (iii) ball milling of partially nanocrystalline ribbons (obtained initially as amorphous and nanocrystallized by annealing at 550degreesC for 1 h). Strong influence of powder manufacture method and milling time on magnetic softness was observed. Ball milled nanocrystalline ribbon exhibited the lowest coercive field Hc, while mechanically alloyed elemental powders - the highest one. In all cases Hc increased with processing time. The observed magnetic hardening of very soft nanocrystalline Finemet ribbon with the milling time was due to the decreasing size of the powder particles.