Comparison on the magnetic properties, phase evolution and microstructure of directly quenched Pr-Fe-Ti-B-based ribbons and rods

Magnetic properties, phase evolution, and microstructure of directly quenched PrxFe82.5 (x) yTi2.5ZryB15 (x = 7-11; y = 0 and 0.5) alloys, including ribbons with about 0.2 mm in thickness and rod magnets with 0.9 mm in diameter, have been systematically studied. Due to the uniformly finer microstructure, resulted from the higher cooling rate, PrxFe82.5 xTi2.5B15 (x = 9-11) ribbons showed better magnetic properties as compared to PrxFe82.5 xTi2.5B15 (x = 9-11) rods. Nevertheless, the improved maximum magnetic energy product (BH)(max) with higher intrinsic coercivity (H-i(c)) of 12.5-13.8 kOe and enlarged applicable composition range (x = 8-10.5) could be obtained in Zr-substituted PrxFe82 xZr0.5Ti2.5B15 rods as a result of grain refinement by Zr substitution for Fe. The optimal magnetic properties of B-r = 7.1 kG, H-i(c) = 15.0 - kOe, and (BH)(max) = 8.6 MGOe, and B-r = 5.9 kG, H-i(c) = 14.5 kOe and (BH)(max) = 7.6 MGOe were obtained for Pr9.5Fe73Ti2.5B15 ribbons and Pr9.5Fe72.5Ti2.5Zr0.5B15 rod magnet, respectively. (C) 2012 Elsevier B.V. All rights reserved.