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

• Published in: Journal of magnetism and magnetic materials Vol. 501; p. 166316
• Main Authors: Heddad, Athar, Chazal, Hervé, Geoffroy, Olivier, Demier, Alain, Gony, Bashar, Waeckerlé, Thierry, Flury, Sébastien
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2020; Elsevier BV; Elsevier
• Subjects: Anisotropy; Boosting effect; Coils; Computer simulation; Crystallization; Electric power; Engineering Sciences; Field annealing; Field impact; Finemet; Induced anisotropy; Legislation; Memory effect; Nanocrystals; One step annealing; Polarization; Sample holders; Shell model; Toroids; Field annealing; Shell model; Induced anisotropy; One step annealing; Boosting effect; Field impact; Finemet; Memory effect
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.166316

•Investigation of the memory effect underlying the establishment of induced anisotropy.•Experiment method to boost the field applied to the treated cores during annealing.•Polarization during the annealing have been investigated through simulation process. We study the relation between the induced anisotropy obtained on nanocrystalline Fe73.0Cu1.1Nb3.1Si15.7B7.1 toroidal cores crystallized under transverse field at 570 °C, and the polarization Jc 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 μ0Ha=33mT, playing on the proportion between treated and SiFe cores, effective field ranging between 33mT and 230mT were obtained inside treated cores. As a result, the induced anisotropy at the scale of the alloys at the end of crystallization range from Ku=12J/m3 to Ku=20J/m3. To simulate the evolution of Jc 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 Jcor(H) at the scale of the core reflects the law JcH featured by nanograins during the crystallization process. JcH was modelized as a function of the crystallized fraction fc. The relation between the simulated Jc and the experimental final values of Ku/fc (i.e. the anisotropy in nanograins) was then studied. This was done considering the polarization 〈Jc〉 averaged on the entire crystallization process, wondering about a possible memory effect.