Simultaneously improved corrosion resistance and magnetic properties of α-Fe/Nd2Fe14B type nanocomposite magnets by interfacial modification.

Nanocomposite exchange coupled magnets are most likely the next-generation magnets because of their potentially high energy products. However, their corrosion resistance is a serious concern. The electrochemical behaviour of the nanocomposite magnets is largely unknown. In this study, we investigated the corrosion behaviours of α-Fe/Nd 2 Fe 14 B type nanocomposite magnets in a 3.5 wt% NaCl solution at room temperature using an electrochemical technique. Our results demonstrate that microstructure coarsening can improve the corrosion performance of the magnets, but it greatly degrades the magnetic properties. To enhance the corrosion resistance without scarifying the magnetic performance of the magnets, an amorphous phase with good corrosion resistance is introduced to the grain boundary of α-Fe/Nd 2 Fe 14 B type nanocomposite magnets by controlled melt-spinning process or adding Nb element. The nanocomposite magnets with an interfacial amorphous phase exhibit a lower corrosion current density (22.7 μA/cm 2 ) and higher maximum energy product (23 MGOe) than the magnets without an interfacial amorphous phase. These results indicate that the interfacial modification is beneficial to the improvement of both corrosion resistance and magnetic properties. [ABSTRACT FROM AUTHOR]