Segmentation and Alignment of Nd₂Fe₁₄B Platelets in Nd-Cu Eutectic Alloys Using the Electromagnetic Vibration Technique

An anisotropic Nd₂Fe₁₄B magnet has been of particular significance in engineering, which is usually produced via powder metallurgy. In this study, we report on the production of an anisotropic magnet by solidifying two alloys, i.e., Nd₇₀Cu₃₀-30, 50 wt pct Nd₂Fe₁₄B from the semisolid state using the electromagnetic vibration (EMV) technique. The solidification structures are observed, and the crystalline orientations of the Nd₂Fe₁₄B intermetallic compounds are revealed by electron backscatter diffraction (EBSD) patterns. It is found that the two-step EMV processing is effective in segmenting the developed Nd₂Fe₁₄B compound into fine laths and then aligning these platelets with their easy magnetization directions parallel to that of the static magnetic field. The magnetic properties measured by a vibrating sample magnetometer (VSM) indicate that the specimen with the well-aligned Nd₂Fe₁₄B platelets exhibits a strong anisotropy in magnetism. The segmentation and alignment mechanisms are discussed when considering the EMV imposition parameters, the difference of electrical resistivity between the Nd₂Fe₁₄B compound and the eutectic melt, and the role of the static magnetic field in the present processing condition. The two-step EMV processing technique is promising and expected to provide a new alternative for the simple production of anisotropic Nd₂Fe₁₄B magnets via solidification only instead of conventional powder metallurgy.