Impact of the magnitude of the magnetization on the induced anisotropy in transverse field annealed nanocrystalline cores

Abstract We study the relation between the induced anisotropy obtained on nanocrystalline Fe 73.0 Cu 1.1 Nb 3.1 Si 15.7 B 7.1 toroidal cores crystallized under transverse field at 570 °C, and the polarization J c of nanograins. To do this, an original disposition is used, mixing treated cores with cores made of electrotechnical SiFe alloy, featuring same geometry, using the interfacial magnetic charges to increase the field in treated cores. The field supplied by the coil being μ 0 H a = 33 m T , playing on the proportion between treated and SiFe cores, effective field ranging between 33 m T and 230 m T were obtained inside treated cores. As a result, the induced anisotropy at the scale of the alloys at the end of crystallization range from K u = 12 J / m 3 to K u = 20 J / m 3 . To simulate the evolution of J c during the crystallization process, the configuration of treated and SiFe cores in the sample holder was implemented in Altair FluxT FEM simulation environment with the dedicated polarization laws. Dealing with treated cores, the law J cor ( H ) at the scale of the core reflects the law J c H featured by nanograins during the crystallization process. J c H was modelized as a function of the crystallized fraction f c . The relation between the simulated J c and the experimental final values of K u / f c (i.e. the anisotropy in nanograins) was then studied. This was done considering the polarization 〈 J c 〉 averaged on the entire crystallization process, wondering about a possible memory effect.