Crystalline orientation control of the platelet Nd2Fe14B phase to produce magnetic anisotropy via electromagnetic vibration processing.

ABSTRACT

Controlled crystalline orientation of the discontinuous phase in a composite enables the production of improved anisotropic properties, e.g., well-aligned Nd2Fe14B platelets by hot pressing and then soaking in a low-melting Nd-Cu eutectic melt to infiltrate to grain boundary. Alternatively, an anisotropic magnet can be fabricated by sintering Nd2Fe14B powder pre-aligned with a static magnetic field. In this study, we used a two-step electromagnetic vibration (EMV) technique to solidify the Nd70Cu30-30wt% Nd2Fe14B alloy, by which the magnetic Nd2Fe14B compound could be segmented into short laths and the easy magnetisation axes of these discontinuous platelets could be highly aligned, as revealed by electron backscatter diffraction (EBSD) patterns. Magnetic properties showed that the alloy exhibited strong anisotropy in its magnetism. Our present results opened a new avenue for the simple production of anisotropic Nd2Fe14B magnets via solidification without the powder metallurgy routine. Moreover, the technique is highly expected to be applied to other systems, e.g., graphene-reinforced metallic and/or polymer composites in which the alignment of graphene can maximise the anisotropy in the thermal or electrical properties of the composites.