Influence of a small addition of Nd on structure and magnetic properties of nanocrystalline Fe-B alloys

The influence of the addition of a few atomic percent of Nd on the structure and magnetic properties of Fe-B alloys was investigated. It is found that nanocrystalline Fe-B alloys with a small amount of Nd consist of body-centered-tetragonal Fe3B and α-Fe phases. A small addition of Nd causes a dramatic change of magnetic properties from soft magnetic to hard magnetic. With increasing Nd content the coercivity increases from 0.2 to 2.3 kOe. High remanence and maximum energy product have been obtained in (Fe,Nd)3B/α-Fe magnets and is explained by exchange coupling at interface separating nanocrystalline hard magnetic phase (Fe,Nd)3B and soft magnetic phase α-Fe.