High coercivity low dysprosium (terbium) NdFeB magnet based on crystal boundary modification

Abstract

The invention relates to material capable of improving intrinsic coercivity of high NdFeB magnet. The high coercivity low arrowhead (terbium) NdFeB magnet based on crystal boundary modification is characterized in that a certain amount of Ag element is located in a crystal boundary on the basis of raw magnet; precipitation of Fe elements in the crystal boundary can be basically eliminated; the magnet possesses higher intrinsic coercivity than un-modified alloy; less dysprosium (terbium) is required, so intrinsic coercivity can be improved and dysprosium (terbium) element use amount can be reduced; and the magnet can be applied to various occasions requiring high intrinsic coersivity, low cost and high use temperature.

Description

technical field [0001] The invention relates to a method for improving intrinsic coercive force, reducing the amount of dysprosium (terbium), and using R 2 Fe 14 B structure compound (R is rare earth) is a grain boundary improved permanent magnet material with the main phase, which can meet the needs of high coercive force, low-cost bulk NdFeB permanent magnets, and can be used for applications where the operating temperature is higher than room temperature. Suitable occasions for various needs. Background technique [0002] Heavy rare earth dysprosium is a strategic resource with multiple uses and limited reserves. Dysprosium must be used in everything involving lasers, nuclear reactors, computer hard disks, gas-electric hybrid engines, etc. In recent years, as the consumption of Nd-Fe-B in gas-electric hybrid and pure electric vehicles has increased year by year, the demand for dysprosium has been driven up. The working temperature of Nd-Fe-B magnets on gas-electric hy...

AI Technical Summary

Problems solved by technology

However, when these nonmagnetic elements are used to dope NdFeB magnets, ferromagnetic elements such as Fe and Co segregate at the grain boundaries, and the dopant elements dissolve in Nd 2 Fe 14 Inside the B grain, it has a negative impact on the residual magnetization of the magnet and restricts the further improvement of the coercive force

As reported in literature: H. Sepehri-Amin, T. Ohkubo, T. Shima, K. Hono, Grain boundary and interface chemistry of an Nd-Fe-B-based sintered magnet, Acta Mater., 60 (2012) 819-830 The content of Fe+Co in the grain boundary of NdFeB magnets with a small amount of Cu added is as high as 65 at.% ( figure 2 ), and the grain boundary phase is ferromagnetic, resulting in a relative Nd 2 Fe 14 The magnetic isolation effect of B grains is weakened, and the Nd 2 Fe 14 A magnetic coupling effect will occur between B grains, which hinders the further improvement of the intrinsic coercive force of the magnet

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