Manufacturing method of light rare earth-copper alloy NdFeB magnet with grain boundary being low melting point

Abstract

The invention provides a manufacturing method of a light rare earth-copper alloy NdFeB magnet with the grain boundary being a low melting point and belongs to the field of rare earth permanent magnetic materials. According to the manufacturing steps, a NdFeB main alloy ingot with the near stoichiometric proportion being 2:14:1 is smashed into 3-5 micron powder particles, light rare earth-copper alloy powder with the weight fraction being 3-8% and the average particle size being 0.1-3 microns is added in the powder particles, the light rare earth-copper alloy powder and the power particles are evenly mixed, magnetic field compression, isostatic pressing and sintering densification are performed, and the product is obtained after thermal treatment. The light rare earth-copper alloy is both a liquid phase sintering additive and a grain boundary phase, and the light rare earth-copper alloy and the 2:14:1 main phase have good wettability. The manufacturing method has the advantages that the light rare earth-copper alloy is evenly distributed on the grain boundary of the 2:14:1 main phase, the exchange coupling effect between grains of the 2:14:1 main phase is effectively hindered, high coercive force can be acquired easily, meanwhile, low-temperature sintering can be achieved, high-temperature tempering thermal treatment is omitted, the process is simplified, and energy is saved.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, and in particular relates to a preparation method of a neodymium-iron-boron magnet whose low melting point grain boundary is a light rare earth-copper alloy. Background technique [0002] The sintered NdFeB magnet known as the "Magnetic King" has become the core functional material in the fields of electric power, telecommunications, automobiles, computers, biomedicine and household appliances, and is being used in the manufacture of hundreds of kilowatts of electric (or hybrid electric) vehicles. Generators, motors, and permanent magnet motors for wind power generation in the megawatt range. [0003] The microstructure of sintered Nd-Fe-B magnets usually has the following characteristics: (1) consists of 2:14:1 phase and Nd-rich phase at grain boundaries; (2) Nd-rich phase is distributed along grain boundaries or at the intersection of grain boundaries, The Nd-rich phases di...

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Problems solved by technology

[0004] The orientation and density of sintered NdFeB magnets have reached more than 98%, so its remanence and magnetic energy product have reached more than 90% of the theoretical value, while the coercive force is less than 30% of the theoretical value, mainly due to the actual There is a large gap between the microstructure and the ideal microstructure: the main phase grains are not uniform and small, resulting in low coercive force; the magnetocrystalline anisotropy constant K1 of the surface layer of the main phase grains in 2:14:1 is low, and the microstructure is defective. Many, large scattered magnetic fields, the most likely to form reverse magnetization domain nuclei, resulting in low coercive force; the grain boundary Nd-rich phase cannot be continuously distributed in a thin layer between the 2:14:1 phase grains, and magnetic isolation cannot be effectively realized. The 2:14:1 phase is very easy to generate reverse magnetization domains between grains, which reduces the coercive force of the magnet