Microstructure and magnetic properties of Co58Ni10Fe5B16Si11 and Co58Ni10Fe5B16Si11–Al2O3 bulk amorphous coatings prepared by plasma spraying

Abstract

Abstract The bulk soft magnetic glassy Co58Ni10Fe5B16Si11 alloy specimens have been prepared by plasma spray deposition. In order to increase resistivity of the material, the bulk Co58Ni10Fe5B16Si11–Al2O3 composite materials were fabricated. The investigations of structure and magnetic properties of the bulk samples were carried out by X-ray diffraction, electron microscopy and magnetic measurements. The relation of the structural features and magnetic characteristics of the bulk coating to the main parameters of the deposition regimes was determined. Optimized plasma spray deposition parameters allowed obtaining bulk glassy samples with magnetic parameters that are not inferior to the characteristics of a thermally treated rapidly quenched ribbon with the same composition. It was found that the bulk amorphous coatings can be characterized as a heterophase system. The relaxation annealing of the Co58Ni10Fe5B16Si11 bulk coating leads to a phase transition in this alloy in the precrystallization temperature range. The magnetic properties of the both kinds of coatings are correlated with changes in the microstructure. The appearance of nanocrystalline phase with TC˜640 K during relaxation heat treatment leads to a decrease of the coercivity and to an increase of the permeability. A comparison between the magnetic properties of the CoNiFe-BSi coating and (CoNiFe-BSi)–Al2O3, composite coating is carried out.