Hysteresis modeling and microstructural analysis of soft amorphous alloys

The dynamic Preisach model is applied to the study of Fe-based and Co-based amorphous alloys, characterized by different microstructural conditions. It is shown that all static and dynamic hysteresis properties are correctly predicted by the dynamic Preisach model by associating with each material a structural parameter, λ, which represents the linear dimension of the correlation regions providing coherent magnetization changes. The dependence of this correlation length on annealing treatments is compared with Kerr-effect domain observations and structural data obtained by differential scanning calorimetry. It is found that λ has a role comparable to that of grain size in micro-crystalline alloys. In particular, it is shown that the linear relation holds, HC=Hc0 + c/λ, between the static coercive field Hc and 1/λ, where the slope c depends on the magnetostriction constant of the material and the amount of quenched-in stresses, while the offset Hc0 is connected to surface characteristics