Effect of hydrogenation-disproportionation-desorption-recombination powder processing on the demagnetization process of Nd-Fe-B sintered magnets analyzed by soft X-ray magnetic circular dichroism microscopy

The demagnetization process of a variety of Nd-Fe-B-based magnets produced using different manufacturing techniques are studied by soft X-ray magnetic circular dichroism microscopy. The four magnets studied include a hot deformed magnet, sintered magnets produced from either a N2 jet-milled or a He jet-milled fine powder, and a magnet produced by hydrogenation-disproportionation-desorption-recombination (HDDR) followed by He jetmilling. The coercivity of the HDDR processed magnet is lower than the magnets produced with N2 jet-milled powder even though the size of the grains is smaller. By following the magnetic domain reversal behavior during the demagnetization process, it was found that, while the magnets produced with N2 jet-milled powder and the hot deformed magnet presents a predominance of the reversed magnetic domain propagation, in the HDDR processed magnet the nucleation of individual grains occurs before the reversed magnetic domains propagate. This behavior is associated with a decreased nucleation field of each grain.

Automated summary

The demagnetization process of Nd-Fe-B-based magnets produced using different manufacturing techniques was studied using soft X-ray magnetic circular dichroism microscopy. The study found that the coercivity of the HDDR processed magnet is lower than the magnets produced with N2 jet-milled powder, even though the grain size is smaller. Additionally, it was observed that in the HDDR processed magnet, nucleation of individual grains occurs before the reversed magnetic domains propagate.