A method for improving the performance of sintered NdFeB magnets

Abstract

The invention discloses a method for improving the performance of a sintered NdFeB magnet. Its specific operation method is as follows: (1) prepare NdFeB powder by conventional method; (2) take a metal or alloy powder M, and carry out surface oxidation treatment on powder M; (3) oxidize the surface by double alloy method The powder is mixed into the NdFeB powder; (4) The uniformly mixed powder is molded and pressed and then sintered, and the sintered sample is annealed to obtain a sintered NdFeB magnet. The beneficial effects of the present invention are: 1. Replace the position of iron in the NdFeB unit cell, repair crystal surface defects, and make the crystal plane smooth; 2. Form a uniform layer of non-ferromagnetic phase in the grain boundary phase, weaken the phase The magnetic exchange coupling between adjacent crystals eliminates the domain inversion phenomenon caused by the domain wall movement during the demagnetization process.

Description

technical field [0001] The invention relates to the relevant technical field of sintered NdFeB magnets, in particular to a method for improving the performance of sintered NdFeB magnets. Background technique [0002] The oxygen content in sintered NdFeB magnets has an important impact on the performance of the magnet. When the NdFeB magnet contains too much oxygen, the magnetic properties of the material will be significantly reduced. The main reason is that oxygen will oxidize the grain boundary phase. Neodymium phase, causing the neodymium-rich phase to shrink and concentrate in the triangular connection area of ​​the grain boundary during sintering, instead of being evenly distributed among the crystal planes. But this does not mean that the lower the oxygen content of the magnet in NdFeB, the better its performance. Proper oxidation can effectively improve the coercive force of the magnet, because the Nd-rich phase oxidized at the grain boundary edge provides a pinning ...

AI Technical Summary

Problems solved by technology

[0004] In general, the grain boundary phases in sintered NdFeB magnets contain relatively high oxygen, but usually they are unevenly distributed in the grain boundaries, and are usually enriched in the triangular connection areas of the crystal, while the crystal planes between crystal planes The neodymium-rich phases of the Nd-rich phase will usually be thin or even absent, resulting in direct contact between the crystal plane and the crystal plane

[0005] On the other hand, NdFeB magnets undergo hydrogen breaking and jet milling stages before sintering, resulting in crystal fractures and uneven crystal planes. Although sintered at high temperature, the defect state of crystal planes is partially eliminated, but some are retained.

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