Abstract Scope |
Fe-based nanocrystalline alloys are materials with excellent soft-magnetic properties, showing very low coercivity, high permeability and a magnetic saturation of 1.2-1.3 T. These properties originate from their particular structure, which in the case of e.g. Finemet or Vitroperm consists of bcc (Fe,Si) nanograins embedded in a remnant amorphous matrix. However, these alloys can be obtained in nanocrystalline form only by annealing the amorphous precursor, i.e. the metallic glass (MG) ribbon. Recently, we demonstrated the possibility of casting similar alloys in bulk form and elucidated the crystallization mechanism by time-resolved X-ray diffraction studies. Here we show the possibility to control the resulting macroscopic magnetic properties by tailoring the structure upon thermal annealing. In contrast to the known MG ribbons, our bulk samples build by primary crystallization distorted bcc (Fe,Co) nanocrystals, with the Cu clusters not necessarily acting as centers for the nanocrystallization. |