Anisotropic Consolidation Behavior of Isotropic Nd–Fe–B HDDR Powders During Hot-Deformation

In this paper, the anisotropic consolidation behavior of isotropic Nd-Fe-B HDDR powders has been studied as a function of the strain, strain rate, and processing temperature. The compacts, produced by hot-pressing at 700 °C under 400 MPa in vacuum, were subjected to die-upsetting at 700 °C and 800 °C with different deformation conditions of strain rate 0.01-0.001 s
^-1
and strain 0.5-1.5. After die-upset, the coercivity and remanence decreased and increased with increasing strain, respectively, with the change of grain morphology from the sphere to platelet. And the high deformation temperature and slow deformation rate reduce the coercivity further. The coercivity of die-upset magnet, produced at 700 °C with a strain of 1.4 and a strain rate of 0.001 s
^-1
, was largely increased about 2 kOe after post-annealing at 800 °C. The maximum coercivity, remanence, and (BH)max were 10.4 kOe, 12.4 kG, and 35.6 MGOe, respectively.