DIE-UPSET ND-FE-CO-B MAGNETS FROM BLENDS OF DISSIMILAR RIBBONS

We prepared die-upset Nd-Fe-Co-B magnets from melt-spun ribbon powders which were a series of blends of two ribbon alloys. One alloy was alw ays ternary Nd-Fe-B (no cobalt), and in the other cobalt replaced up t o half of the iron. Differential scanning calorimeter measurements rev ealed that during hot working, the cobalt diffused across ribbon bound aries, effectively redistributing the transition metal concentration t hroughout the magnet. Instead of anomalies indicating the Curie temper atures of the two original ribbon compositions, we found a single tran sition consistent with the average cobalt concentration in the magnet. However, the transition was broader than expected, suggesting that th e homogenization was incomplete. These results are new evidence of mas sive diffusion occurring between ribbons, changing the microstructure and facilitating the deformation of the otherwise rigid 2-14-1 magnet.