Disaccommodation of Amorphous Magnetic Alloy Fe5Co70Si10B15

Time decrease of initial permeability µi after demagnetization (disaccommodation, DA) was measured for amorphous alloy Fe5Co70Si10B15. Two types in DA, named DAI and DAII, were observed. DAI is a part of DA where µi recovers to the original value by demagnetization similarly to ordinary DA. In DAII µi does not recover by the demagnetization and continuously decreases, which seems to be a kind of ageing phenomenon. Magnitude of DA, DI is 4 % between t1=0.03 and t2=4 minutes and DII is 7% (t2=1 hour) at room temperature. Activation energy QI estimated from the thermal change of DI is approximately 0.8 eV and QII is 1.5 eV. Annealing treatment at high temperature decreases both DI and DII to 1 %, increases QI to 1.1 eV and does not affect QII. It is concluded that the DA is due to the local induced anisotropy in 180° magnetic domain walls.