Phase composition, structure and magnetic behaviour of low neodymium Nd-Fe-B permanent magnets

Abstract

Phase composition, structure and magnetic behaviour of two low neodymium hard magnetic materials differing in way of preparation, centrifugal atomization and melt spinning, were compared using Mössbauer spectroscopy, X-ray diffraction, thermomagnetic analysis and SQUID magnetic measurements. Better hard magnetic characteristics of the melt-spun material are explained on the basis of the differences in content of surface and/or interface Fe(Nd, B) phases. Their remarkable presence in the centrifugally atomized material lowers the content of Fe3B, Fe2B, α-Fe, and Nd2Fe14B phases that are responsible for the magnetic qualities of the material. There are just subtle differences in the phase composition of both materials after thermomagnetic measurement, where the a-Fe phase prevails as a product of thermal decomposition.