Magnetic hardening of Ce_2Fe_(14)B

摘要

We report an effort to optimize the room-temperature permanent magnet properties of Ce-Fe-B materials rapidly solidified by melt spinning. Starting alloy compositions in the ternary phase diagram were selected systematically. Ribbons were melt spun from them at a quench wheel velocity of 35 m/s, corresponding to a solidification rate high enough to yield mostly amorphous or nanocrystalline material. Heat treatment above 450 ℃ crystallizes Ce_2Fe_(14)B, as x-ray diffraction clearly indicates, with the concomitant development of hard magnetic properties. The anneal temperature yielding optimum remanence B_r, intrinsic coercivity H_(ci), and energy product (BH)_(max) was determined in each case. For the ingot composition Ce_(17)Fe_(78)B_6, we obtain B_r =4.9 kG, H_(ci) = 6.2 kOe, and energy product (BH)_(max) = 4.1 MGOe in ribbons comprised principally of Ce_2Fe_(14)B. This composition differs substantially from the optimum Nd_(13)Fe_(82)B_5 stoichiometry for melt-spun magnets based on Nd_2Fe_(14)B and can be understood from a comparison of the distinct Ce-Fe-B and Nd-Fe-B phase diagrams.