Abstract：Abstract: Rare Earth Permanent Magnet (REPM) are widely used due to their high energy density. Compared with conventional polycrystalline REPM, nanostructural magnets exhibit extraordinary magnetic properties due to their unique microstructure. As a result, nanostructural REPM had drawn considerable attention during the last decades. This paper is a comprehensive review of research for the development of nanostructural permanent magnets in both the R-Co (R=Sm, Pr) and the R-Fe-B (R=Nd, Pr) systems. The experimental preparation techniques for nanostructural R-Co and R-Fe-B magnets including melt-spinning, high energy ball milling (HEBM), surfactant-assisted ball milling (SABM), and mechanochemical synthesis are introduced. Consolidation techniques used to make bulk magnets from the particle precursors are also discussed including spark plasma sintering (SPS), inductive heating compaction (IHC), shock wave compaction (SWC), combustion given compaction (CDC), and high-pressure warm compaction (HPWC). The structural and magnetic properties of both R-Co and R-Co/Fe are discussed for both isotropic and anisotropic magnets. The magnetic properties of single phase isotropic and anisotropic R-Fe-B nanostructural magnets are discussed together with R-Fe-B/Fe(Co) magnets composed of a fine mixture of exchange-coupled magnetically soft and hard grains.
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