Effect of boron content on magnetic properties and microstructure of PrFeCoBNb HDDR permanent magnets

The effect of boron content (4-8 at%) on the microstructure of Pr-Fe-Co-B-Nb alloys has been investigated using scanning electron microscopy and energy dispersive x-ray analysis. Permanent magnets were prepared from cast and annealed alloys using the hydrogenation, disproportionation, desorption and recombination process. The magnetic properties of magnets with the composition Pr14Fe69.9−xCo16BxNb0.1 were assessed using a permeameter technique. It has been shown that annealing and boron content have a dramatic effect on the microstructure of the alloy and also on the magnetic behaviour of these bonded magnets.