Structure and magnetic properties of bulk isotropic and anisotropic Nd2Fe14B/α-Fe nanocomposite permanent magnets with different α-Fe contents.

Chemical coating, hot compaction, and hot deformation techniques have been applied to prepare bulk isotropic and anisotropic Nd₂Fe₁₄B/α-Fe nanocomposite magnets. The effect of α-Fe content on the structure and magnetic properties of the magnets were studied. For the isotropic magnets, the remanence (Br) increases as the α-Fe content increases, while the coercive force (Hci) drops simultaneously. For the anisotropic magnets, the Br rises first, peaking at 2 vol % of α-Fe content, then falls as the α-Fe content increases, and Hci drops significantly for all the α-Fe containing anisotropic magnets. Crystal structure analysis shows that only the magnets with no more than 2 vol % α-Fe exhibit strong c-axis crystal texture of Nd₂Fe₁₄B phase after deformation. Microstructure observation also shows that there are many Nd₂Fe₁₄B equiaxial grains even after hot deformation in the magnets with α-Fe more than 2 vol %. [ABSTRACT FROM AUTHOR]