Anisotropic powder from sintered NdFeB magnets by the HDDR processing route

Sintered NdFeB-based scrap magnets were recovered and processed using the HD and HDDR routes. The effects of varying the HDDR processing temperature were investigated (over the range 835-930 degrees C). The disproportion was carried out with a pressure ramp to a maximum of 1000 mbar hydrogen pressure with a 1 h hold time at each step and the optimum recombination conditions were set at 100 mbar with a 20 min hold time. Anisotropic NdFeB powder was produced in all cases with the best magnetic properties achieved at a processing temperature of 880 degrees C, producing powder with a remanence of 1.10(+/- 0.02) T and an intrinsic coercivity of 800 (+/- 16) kA m(-1) and giving a (BH)(max) of 129(+/- 2.5) kJ m(-3). (C) 2011 Published by Elsevier B.V.