Permeameter measurements of anisotropic PrFeCoBZr hydrogenation disproportionation desorption and recombination (HDDR) magnets

The magnetic properties of HDDR magnets prepared from a Pr13.7Fe63.5Co16.7B 6Zr0.1 alloy using an isostatic press technique have been investigated by m eans of permeameter measurements. It has been shown that it is possible to produce highly anisotropic HDDR material from this alloy in the annealed (1 100 degrees C for 20 h) state in a 13 g sample. Normalised (100% density) r emanence in the easy direction of an aligned magnet was found to be 1000 +/ - 20 mT, whereas, in the hard direction it was 442 +/- 10 mT. Similar studi es have been performed on a Nd16Fe75.9B8Zr0.1 alloy as a comparison. The in trinsic coercivity (1050 kA/m) of the NdFeBZr HDDR magnet was much higher t han that of the Pr-based HDDR permanent magnets (732 kA/m) but there was a much lower degree of anisotropy in the case of the former in the as-cast st ate and when subjected to an identical HDDR treatment. (C) 1999 Elsevier Sc ience B.V. All rights reserved.