| 简介 |
PROBLEM TO BE SOLVED : To provide a cerium-containing neodymium iron boron magnet and a method for manufacturing such magnet.
SOLUTION : A method for manufacturing a cerium-containing neodymium iron boron magnet according to the present invention comprises : a step for feeding a part of raw materials, including pure iron, boron-iron, and rare earth fluoride into a melting container of a vacuum melting chamber under a vacuum condition; a step for feeding another raw material including a rare earth element into the melting container of the vacuum melting chamber and then, dropping a liquid alloy in the state of being melted after the completion of refining on a water-cooled rotary roller to form an alloy piece; and steps for performing, on two or more kinds of alloy pieces including the alloy piece thus formed and differing in component, the actions including hydrogen pulverization, air flow pulverization/milling, compaction into a magnet body, preliminary sintering in vacuum, machining, and sintering. The cerium-containing neodymium iron boron magnet is 7.5-7.7 g/cm3 in density, and 3-7 μm in crystal average particle diameter. The cerium-containing neodymium iron boron magnet includes crystal phases and crystal grain boundaries. The crystal grain boundaries are distributed around the crystal phases. The crystal phases include rare earth elements, especially at least La, Ce, Pr and Nd. The crystal grain boundaries include Ce, N and F elements. There is a Laves phase including a Tb element between the crystal phase and the crystal grain boundary. In the cerium-containing neodymium iron boron magnet, the total weight of La and Ce accounts for 1-69% of the total weight of the rare earth elements.
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