MAGNETIC-BEHAVIOR OF FE-NB AND FE-ZR ALLOYS NANOCRYSTALLIZED BY MEANS OF FLASH ANNEALING

Recently nanocrystalline alloys obtained from Fe-rich amorphous metallic glasses have shown excellent soft magnetic properties for technical applications. They include 4d elements like Nb or Zr for obtaining nanometer-size crystals after heat treatments of about 1 h at temperatures around 500-degrees-C. Flash annealing, using an electrical current flowing along the sample, is a useful method for performing heat treatments in short periods of time without need of controlled atmosphere. Grain sizes in the range 8-20 nm were determined from x-ray diffraction in crystallized alloys prepared by flash annealing technique. These are grain sizes even smaller than the ones obtained in furnace treated samples. Magnetic softening of the alloys is observed after the heating. Magnetization work, permeability, coercitive force, etc., are very similar after applying both types of treatments.