Study of the effect of Zr-substitution on the HDDR characteristics of Nd-Fe-B-type alloys

Alloys with compositions based on Nd/sub 16/Fe/sub 76-x/B/sub 8/Zr/sub x/ (where x=0-2.0) have been studied to see the effect of Zr-substitution on the hydrogenation, disproportionation, desorption, recombination (HDDR) characteristic of the Nd-Fe-B-type alloys. The HDDR characteristics of the alloys were investigated by means of DTA, TPA and magnetic measurement. It has been found that a small substitution (0.1 at%) of Zr for Fe in the Nd-Fe-B-type alloy retards the disproportionation kinetics of the hydrogenated material. The desorption characteristic of the disproportionated materials has been found not to be affected significantly by the Zr-substitution. The Zr-substitution has been found to facilitate the recombination reaction. The peak coercivity of the HDDR treated material has been found to increase with increasing Zr-content. It has also been revealed that the Zr-substitution suppressed the degradation of the coercivity due to the excessive grain growth of the recombined grains on prolonged recombination.