Creation of nano-magnet model thin films with HRE ideal interface for reducing rare-metal

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Nd-Fe-B sintered magnets have a potential for wide application such as a high performance motor for hybrid electric vehicle (HEV) and direct drive widow turbine. Recently, a new technique to enhance the coercivity H_c by using lesser amount of heavy rare earth element (HRE) has been developed, which is called a grain boundary diffusion process “GBDP". On the other hand, it is believed that the Nd-rich phase plays an important role in the coercivity enhancement in Nd-Fe-B magnets. In the case of GBDP magnets with Dy, however, it is still not clear whether only the Dy-rich shell or both Dy-shell and the Nd-rich phase are indispensible for the high H_c. Therefore, we fabricated a model interface system, which consists of the Nd_2Fe_<14>B layer with Dy overlayer and Dy/Nd double over-layer in order to study the relationship between microstructure near the interface and the coercivity.