A kind of preparation method of nanocrystalline rare earth permanent magnetic alloy powder

Abstract

The invention belongs to the technical field of the rare-earth permanent magnet material, specifically relating to a method for preparing a nanocrystalline rare-earth permanent magnet alloy powder. The method comprises the following steps of: subjecting a rare-earth alloy to a vacuum smelting step, a vacuum quick quenching step, a crushing and sieving step and a thermal treatment step in this order, wherein the thermal treatment step is microwave heating treatment, the temperature of the thermal treatment is 600-700 DEG C, and the time for the thermal treatment is 1-15 min. The grain size of the nanocrystalline rare-earth permanent magnet alloy powder prepared by the method is 10-30 nm; and the magnetic energy product (BH) m of the magnetic powder reaches up to 120-180 kJ / m3; therefore, the powder has more excellent magnetic performance in contrast with the rare-earth permanent magnet alloy powder prepared by the traditional quick quenching technology which has the magnetic energy product (BH) m within a range of 100-140 kJ / m3.

Description

technical field [0001] The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a preparation method of nanocrystalline rare earth permanent magnet alloy powder. Background technique [0002] Nanocrystalline rare earth permanent magnet material is a new type of high-performance permanent magnet material. This type of material obtains the remanence enhancement effect through the exchange coupling between nanocrystal grains, so it has high remanence, high magnetic energy product and high coercivity. Theoretical calculations by Skomski and Coey et al. show that the highest magnetic energy product of nanocrystalline rare earth permanent magnet materials can reach 1MJ / m 3[1] , which is twice as high as the magnetic energy product of the current best sintered NdFeB magnet. However, the magnetic energy product of nanocrystalline rare earth permanent magnet materials prepared by melt rapid quenching or mechanical ball mill...

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Problems solved by technology

However, the magnetic energy product of nanocrystalline rare earth permanent magnet materials prepared by melt rapid quenching or mechanical ball milling in experiments and production is 100-140kJ / m 3[2-5] , much lower than its theoretical expected value (1MJ / m 3 ), one of the important reasons is that the grain size of the material is too large and the uniformity is poor, which cannot meet the requirements of the theoretical model

[0003] Generally speaking, in the traditional melt rapid quenching process and mechanical ball milling process, the heat treatment process of the alloy generally adopts the traditional heating method [2-5] , that is, according to the principles of heat conduction, convection and radiation, the heat is transferred from the outside to the inside of the alloy, and the alloy is heated from the surface to the inside. This heat treatment method makes the temperature gradient inevitably exist in the alloy, which in turn leads to the inhomogeneity of the internal structure of the material.

However, there is no report on the use of microwave heating technology for the preparation of rapidly quenched nanocrystalline NdFeB permanent magnet materials.

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