Effects of Hydrogenation-Disproportionation-Desorption-Recombination Processing Parameters on the Particle Size of Ultrafine Jet-Milled Nd-Fe-B Powders

The effects of variations in the hydrogenation-disproportionation-desorption-recombination (HDDR) processing parameters on the size of Nd-Fe-B ultrafine powders were investigated. The ultrafine powders were fabricated by hydrogen decrepitation and jet milling of the HDDR alloys. Before pulverization, the crystal grain size of the HDDR alloys obtained by changing the HD processing temperature (THD) varied from 0.27 to 0.55µm, and decreased as THD was lowered. The ultrafine powder of the HDDR alloy became finer as THD decreased, with sizes in the range of 0.33 to 0.58µm. [doi:10.2320/matertrans.M2014273]