Manufacturing method for high coercivity Nd-Fe-B sintered magnets

The two-alloy method with Mn-containing auxiliary flakes enhances the grain boundary structure of Nd-Fe-B sintered magnets, achieving higher coercivity and maintaining magnetic performance through controlled sintering and tempering processes.

JP7725732B2Active Publication Date: 2025-08-19YANTAI ZHENGHAI MAGNETIC MATERIAL CO LTD
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Patent Information

Application Number
JP2024525290
Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2022-07-06
Filing Date
2023-06-07
Publication Date
2025-08-19
Estimated Expiration
2043-06-07

AI Technical Summary

Technical Problem

Existing methods for improving the coercivity of Nd-Fe-B sintered magnets face challenges as they either lead to reduced magnetic performance or insufficient coercivity gains, particularly when using metals like Cu and Al, and there is a need for a more effective method to enhance the grain boundary structure.

Method used

A two-alloy method involving Mn-containing auxiliary alloy flakes is used, where Mn replaces part of the Fe in the main phase, forming a Mn coating layer that reduces Cu and Al intrusion, combined with controlled sintering and tempering processes to produce high-coercivity Nd-Fe-B sintered magnets.

Benefits of technology

The method achieves higher coercivity and maintains magnetic performance by ensuring uniform grain boundary phases, overcoming the limitations of previous techniques and achieving superior coercive forces in the sintered magnets.

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Abstract

The present invention discloses a high coercive force Nd-Fe-B sintered magnet and its manufacturing method and application, the sintered magnet is 100% by mass and contains the following components: R 26-37 wt%, where R is at least one rare earth element including Nd, Mn 0.07-0.23 wt%, B 0.8-1 wt%, M 0.5-4 wt%, where M contains Cu and / or Al, and further contains at least one selected from Co, Ti, Ni, Zr, Ga, and the balance is Fe. The present invention manufactures a Nd-Fe-B sintered magnet by mixing a Mn-containing auxiliary alloy powder with a Mn-free NdFeB main alloy powder, and the Mn-containing auxiliary alloy powder must contain at least one of metallic Cu and Al in addition to Mn element within the scope of the present invention, and Mn replaces part of Fe in the main phase, thereby reducing the amount of beneficial elements dissolved in the main phase at the grain boundary and improving the coercive force.
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Citation Information

Patent Citations

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    WO2009150843A1