ANISOTROPIC AND COERCIVE HDDR ND-FE-B POWDERS PREPARED UNDER MAGNETIC-FIELD

High coercivity Nd-Fe-B powder with H-cj up to 14 kOe was achieved aft er optimisation of the two latest phases of the en-Disproportionation- Desorption-Recrystallisation (HDDR) process. The progression of the so lid gas reaction (Nd-Fe-B/H-2) as analysed by a thermomagnetic balance , has given the possibility to monitor the disproportionation reaction . The first step was to define favourable conditions to develop a cont rolled but uncompleted disproportionation reaction. The second step wa s the application of an high magnetic field of mu(0) H = 7 T during th e DR process. Anisotropic Nd-Fe-B powder was crystallised.