Effect of Desorption Hydrogen Pressure on Anisotropy of HDDR-Treated Nd-Fe-B Powders

Abstract

Anisotropic Nd13.5Fe79.5B7 magnetic powders are obtained by varying the desorption H2-pressure of the hydrogenation disproportionation desorption recombination (HDDR) process. The magnetic powders with a desorption H2-pressure of 10 kPa have the magnetic properties of Br =0.61 T and Mr/Ms =0.67, whereas the magnetic powders obtained with a higher and a lower desorption H2-pressure are isotropic. A lamella crystal is observed in the 10 kPa desorption H2-pressure products and may be related to the anisotropy in the HDDR-treated powders. It suggests that the desorption H2-pressure has great effect on the formation of crystal texture in the HDDR Nd-Fe-B powders.