A New Method for Enhancing the Coercivity of NdFeB Permanent Magnets without Dy
This research was headed by
Kazuhiro Hono
Kazuhiro Hono
An exquisite natural phenomenon that polarity-induced assembly of crystals can occur was discovered. A ZnO rod has a positive and a negative polar end and in a concentric assembly, all rods grow along a single polar end, resulting in different properties. The same could be relevant to other materials too and lead to novel applications.
Figure 1. Scanning electron microscopy images of Nd-Fe-B HDDR magnet powder composed of nanocrystals of 250 nm. (a) Magnet before the diffusion process with the coercivity 16 kOe, and (b) Magnet after the diffusion process with the Nd-Cu alloy, showing that dark magnet crystals are separated by light-colored Nd enriched phases.
Figure 2. Atom probe tomography of the magnet after the diffusion process with the Nd-Cu alloy, showing Nd and Cu enriched layer around the grain boundary. The presence of Nd-enriched layer around 2 nm thick weakens the magnetic coupling between the crystals, thereby improving the coercivity.
