The effects of Zr/Ti substitution for Fe on the magnetic properties, phase evolution and microstructure of directly quenched Nd 9.5Fe7 2.5Ti 3-xZr xB 15 (x50-3) bulk magnets with 0.9 mm diameter have been investigated. Proper Zr substitution for Ti has been found to well modify the phase constitution and refine the grain size from 200-250 to 50-100 nm. Consequently, the magnetic properties of the rods are enhanced remarkably from iHc56.2 kOe and (BH) max55.6 MGOe for Zr free rods to iHc59.2-13.5 kOe and (BH) max56.9-8.2 MGOe for Zr substituted Nd 9.5Fe7 2.5Ti 3-xZr xB 15 rods (x50.5-2). The optimum magnetic properties of Br56.6 kG, iHc59.6 kOe and (BH) max58.2 MGOe can be achieved for the directly cast Nd9.5Fe72.5Ti2.5Zr0.5B15 alloy. ? 2012 W. S. Maney & Son Ltd.
