Abstract: The evaluation of the relative stability of initial permeability has been made of the pre-an- nealed amorphous ferromagnetic alloys Fe_(76)Si_(10)B_(14),Fe_(40)Ni_(38)Mo_4B_(18) and (Fe_(0.1)Ni_(0.35)Co_(0.55))_78Si_8B_(14) by the experimental values of average activation energy and fre- quency factors on the basis of the empirical expression deduced by experimental data of the kinetics of their permeability decay.Calculated results show that the relative stability of permeability is sufficient for practical uses in the temperature range within 100℃,although the permeability instability can not be substantially eliminated.In other words,the permeability decay is considerably small within a period of considerable length.

Key words: permeability decay, activation energy, frequency factor