Sintered neodymium iron boron permanent magnet based on crystal grain recombination and manufacturing method

Abstract

The invention discloses a sintered neodymium iron boron permanent magnet based on crystal grain recombination and a manufacturing method. The permanent magnet has composite main phases that main phases with high heavy rare earth RH content are distributed around main phases with lower heavy rare earth RH content, and no continuous grain boundary phase exists in the composite main phases; average content of heavy rare earth RH on the periphery of the composite main phases is higher than content of heavy rare earth RH in the core part of the composite main phase, and the average crystal grain size of the composite main phases is 6-14mu m; heavy rare earth RH comprises more than one of Dy, Tb, Ho, Gd and Y elements. The manufacturing method comprises steps of first alloy smelting, second alloy smelting, hydrogen decrepitation, alloy plate mixing, jet mill powdering, magnetic field formation, vacuum sintering and aging; the step of first alloy smelting comprises a process of preparing first alloy plates containing Pr and Nd elements; the step of second alloy smelting comprises a process of preparing second alloy plates containing heavy rare earth RH elements.

Description

technical field [0001] The invention belongs to the field of permanent magnet devices, in particular to a sintered NdFeB permanent magnet based on grain recombination and a manufacturing method thereof. Background technique [0002] Corrosion-resistant high-performance permanent magnet is a basic electronic component and electrical component widely used in the world today, mainly used in computers, mobile phones, televisions, automobiles, communications, toys, audio, automation equipment, nuclear magnetic resonance imaging, etc. With the requirements of energy saving and low-carbon economy, high-performance permanent magnets have begun to be applied in energy-saving household appliances, hybrid electric vehicles, wind power generation and other fields. [0003] U.S. Patent No. 7,258,751 authorized on August 21, 2007 and U.S. Patent No. 7,867,343 authorized on January 11, 2011 disclose heat treatment of quick-setting alloy sheets at 400-800°C for 5 minutes to 12 hours. Make ...

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Problems solved by technology

[0003] U.S. Patent No. 7,258,751 authorized on August 21, 2007 and U.S. Patent No. 7,867,343 authorized on January 11, 2011 disclose heat treatment of quick-setting alloy sheets at 400-800°C for 5 minutes to 12 hours. Make the RH element move from the grain boundary phase to the main phase, thereby increasing the coercive force of the rare earth magnet; US Patent No. 7,585,378 authorized on October 8, 2009 discloses a method for manufacturing an alloy for R-T-Q series rare earth magnets. It consists in rapidly cooling the alloy melt to a range of 700-1000°C to form a quick-setting alloy, and then keeping the quick-setting alloy at a temperature of 700-900°C for 15-600 seconds; State-bed airflow milling powder technology, using cyclone collector to collect powder; the disadvantage of fluidized bed is that the bottom material of tens of kg is always kept in the mill, and the powder-making speed is controlled by controlling the weight of the bottom material, which affects the powder-making Particle size, carry large particles, need to take out the bottom material when changing the brand, the bottom material is easy to oxidize; the disadvantage of the cyclone collector is that the fine powder with a particle size of less than 1 μm will be discharged with the exhaust airflow, affecting the product yield and particle size distribution

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