Manufacturing method of rare earth permanent magnet alloy, NdFeB rare earth permanent magnet and manufacturing method

Abstract

The invention discloses a manufacturing method for double-roll cooled rare earth permanent magnet rapidly hardened alloy. The manufacturing method comprises the following steps of heating, fusing and refining neodymium iron boron raw materials into fused alloy liquid under a vacuum or protection condition; pouring the alloy liquid to the outer edge of a first water-cooled rotating roll through a gap of a tundish to form an alloy plate; rotating the alloy plate along with the first rotating roll; separating the alloy plate from the first rotating roll so that the alloy plate drops to the outer edge of a second water-cooled rotating roll; rotating the alloy plate along with the second rotating roll; and separating the alloy plate from the second rotating roll so that the alloy plate drops to form a double-surface-cooled alloy plate. The neodymium iron boron permanent magnet which is made of the alloy has R2T14Q main phases and grain boundary phases, wherein R is selected from elements of Pr, Nd, Dy, La, Ce, Gd, Tb and Ho; T is selected from elements of Fe, Co, Al and Mn; Q is selected from elements of B, N and C; the main phases are isolated from one another by the grain boundary phases; and oxides and nitrides of Pr and Nd are distributed in the grain boundary phases.

Description

technical field [0001] The invention belongs to the field of rare-earth permanent magnets, and in particular relates to a manufacturing method of a double-roller cooled rare-earth permanent-magnet quick-setting alloy, a neodymium-iron-boron rare-earth permanent magnet and a manufacturing method thereof. Background technique [0002] NdFeB rare earth permanent magnet materials, with their excellent magnetic properties, have been used more and more, and are widely used in medical nuclear magnetic resonance imaging, computer hard drives, audio, mobile phones, etc.; with the requirements of energy saving and low-carbon economy , NdFeB rare earth permanent magnet materials have begun to be used in auto parts, household appliances, energy saving and control motors, hybrid vehicles, wind power generation and other fields. [0003] U.S. Patent No. 7,585, the manufacture method of the disclosed neodymium-iron-boron rare earth permanent magnet vacuum quick-setting alloy of 378, this m...

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Problems solved by technology

[0003] U.S. Patent No. 7,585, the manufacture method of the disclosed neodymium-iron-boron rare earth permanent magnet vacuum quick-setting alloy of 378, this method is as figure 1 As shown, the NdFeB raw material is melted in the crucible 1 and cast into the tundish 2, and the alloy liquid overflowing from the tundish is cooled and quickly solidified by the cooling roller 3 to form an alloy sheet 4, and the alloy sheet is thrown to the rotating cylinder 5 with a heater, The temperature of the alloy sheet in the rotating cylinder is kept at 700-900°C; then the alloy sheet is cooled; the feature of this invention is that the alloy is rapidly cooled to 700-900°C, and then the alloy sheet is kept at 700-900°C, and the holding time is from 15 Seconds to less than 600 seconds; Compared with the previous single-roller quick-setting technology and double-roller quick-setting technology, this invention diffuses the heavy rare earth element Dy into the main phase through heat preservation, which improves the coercive force of the magnet. When the temperature is higher than 700°C, the grain boundary phase is a liquid phase. The change of the grain boundary phase will cause abnormal growth of grains, and it is difficult to form uniform grains. From the contact roll surface to the free surface grains are formed by From small to large, uncontrollable consistency

[0004] Chinese patent CN97,217,372.2 discloses the vacuum quick-setting equipment of twin-stick cooling, as figure 2 As shown, the alloy liquid of the equipment is cast into the gap between the cooling roll 7 and the cooling roll 8 through the funnel 6 to form an alloy sheet 9; The temperature of the alloy sheet after roll rolling is higher than 800°C. Although the double-roll rolling solves the problem of double-sided cooling, it cannot meet the requirements of refining grains, improving grain consistency, and thus increasing coercive force; In order to improve the shortcomings of the aforementioned patents, Chinese patent CN01,241,237.6 discloses the technology of adding a cooling roll under the twin-rollers on the basis of twin-roll rolling. Although this invention improves the performance of the aforementioned patents, the production of alloy sheets The thickness is increased, but it is still double-rolled, which cannot solve the problem that the temperature of the alloy sheet leaving the cooling roll is lower than 700 ° C, and cannot achieve the purpose of reducing the amount of heavy rare earth

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