Studying microstructure of sintered magnets Co-25% Sm

Abstract

Metallographic study of sintered rare-earth Co- 25% Sm magnets microstructure of KS-25 brand was carried out by scanning electron force microscopy (EDS-analysis). A dendritic structure with three phases was found: branches of dendrites are SmCo5; interdendritic space is a mixture of two phases SmCo5 and Sm2Co17. Crystals of 1-5 μm of Zr5Co3FeSm compound and inclusions of Sm2O3 samarium of a globular form of 2-10 μm in size were founded also in the microstructure. Study of the domain structure on surfaces perpendicular to magnetization axis by magnetic force microscopy (MFM) showed presence of strong magnetocrystalline anisotropy. Comparison of magnetic images with electron microscopic images of surface made it possible to conclude that SmCo5 dendrites correspond to large domains ∼ 30-50 μm in size and the interdendritic space consisting of a mixture of two phases SmCo5 and Sm2Co17 correspond to a domain structure in labyrinth form with a size of ∼ 3-5 μm. © 2019 Published under licence by IOP Publishing Ltd.