Magnetic permeability relaxation in amorphous Fe62.5Co6Ni7.5Zr6Cu1Nb2B15

The high-frequency initial magnetic permeability and its relaxation have been studied in Fe62.5Co6Ni7.5Zr6Cu1Nb2B15 after heat treatment (both in furnace or via DC Joule heating). The magnetic permeability steadily increases in correspondence of both structural relaxation and nanocrystallisation of the alloy. The intensity of the permeability relaxation (measured between fixed times after demagnetisation) is reduced by structural relaxation but exhibits a sharp maximum immediately before the onset of nanocrystallisation. The nanocrystalline alloy is characterised by a nonzero, if reduced, permeability relaxation.