Dependence of the coercivity HcJ of high energy Nd-Fe-B magnets on the alignment coefficient

Sintered Nd-Fe-B near net-shape magnets with a high remanent polarization of 1.37 T, a coercivity H_cJ of 9.6 kA/cm (12 kOe) and a maximum energy density of 420 kJ/m³ (53 MGOe) are manufactured by rubber isostatic pressing. The optimization of the remanent polarization by an improved alignment process of the powder particles resulted in a decrease of the coercivity by 0.4 kA/cm per% Δf_φ for alignment coefficients in the range 96-98%. For alignment coefficients between 98-99% the decrease of the coercivity even amounts to about -1 kA/cm per% Δf_φ. The temperature coefficients of such magnets amount to -0.11%/K for the remanent polarization and to -0.77%/K for the coercivity in the temperature range 20-100°C