Effect of substituting Pr for Nd on magnetic properties of Nd-Fe-B HDDR powder

The effect of partially substituting Nd by Pr on magnetic properties of HDDR (hydrogenation-decomposition-desorption-recombination)-processed Nd-Fe-Co-B-Ga-Zr powder was studied. It was found that coercivity HcJ of the (Nd1−x,Prx)12.9Febal.Co5.8B6.3Ga0.5Zr0.1 (x = 0-0.40) powder at room temperature is increased with increasing Pr content x, while residual induction was kept almost constant. The increase in HcJ is larger than that expected from the increase in magnetocrystalline anisotropy field Ha of the magnetic phase (Nd,Pr)2Fe14B. This can be attributed to change in grain-boundary microstructures. Temperature-dependence of HcJ in the injection-molded-bonded magnets made from the powders was also examined. It was confirmed that the decrease in HcJ of the magnet with x = 0.24 is kept almost the same as the magnet with no Pr addition in the temperatures ranging from room temperature to 150 °C.