Effects of air annealing on Fe-Si-B-M-Cu (M=Nb, Mo) alloys

Previous works have shown that Nb protects Finemet (Fe73.5Si13.5B9Nb3Cu1) against oxidation. Still, the material must be annealed in a controlled atmosphere to induce nanocrystallization, otherwise, the oxide layer that is formed, deteriorates the soft magnetic properties of the material. Since Nb may be replaced by Mo in Finemet without a significant change in its structure and performance, we studied the effect of the exchange on the oxidation resistance of the alloy. We found that replacing Nb by Mo enhanced oxidation resistance. While Nb-alloy’s permeability was 41.3% smaller when nanocrystallized in air than in vacuum, Mo-alloy’s permeability only decreased by 8.5%. Air annealing would simplify the manufacturing process of Finemet products.Fil: Silveyra, Josefina María. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; Argentina; ArgentinaFil: Illeková, EmÍlia. Slovak Adademy of Sciences; Eslovaqui

Microstructural study of the crystallization of amorphous Fe-Sn-B ribbons

Amorphous Fe78Sn5B17 ribbons were prepared by planar flow casting. The thermodynamic stability and the kinetics of observed phase transformations were monitored by thermal analysis. The structure and morphology of phases forming upon the thermally activated crystallization is studied by X-ray diffraction and transmission electron microscopy. The crystallization begins by nucleation-and-growth of specific nanocrystalline bcc-Fe(Sn) phase, its structure is explored more in details and the role of Sn in its formation is discussed. In the next step of the crystallization a transformation of remaining amorphous matrix to iron borides runs via rather complex process, which is inspected more in details as well.Web of Science61546646

Phase transformations in Mo-doped FINEMETs

In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM. The thermal stability of the alloy was deteriorated as a consequence of Mo’s smaller atomic size. The gradual replacement of Nb by Mo reduced the onset temperature of Fe–Si and of the borides. The Curie temperature of the amorphous phase slightly decreased from 594 K for x=0 to 587 K for x=3. The borides compounds Fe2B and Fe23B6 as well as the (Nb,Mo)5Si3 phase were found to precipitate in the second and third crystallization.Fil: Silveyra, Josefina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; Argentina; Argentina. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; ArgentinaFil: Illeková, Emília. Slovak Academy of Sciences; EslovaquiaFil: Švec, Peter. Slovak Academy of Sciences; EslovaquiaFil: Janičkovič, Dušan. Slovak Academy of Sciences; EslovaquiaFil: Rosales Rivera, Andrés. Universidad Nacional de Colombia; ColombiaFil: Cremaschi, Victoria Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; Argentina; Argentina. Universidad de Buenos Aires. Facultad de Ingenieria. Departamento de Fisica. Laboratorio de Sólidos Amorfos; Argentin

IMPACT OF PHOSPHORUS FOR BORON SUBSTITUTION ON MAGNETIC PROPERTIES OF MAGNETOSTRICTIVE FINEMETS

ABSTRACT Reduction of Si percentage i