Improved corrosion resistance and thermal stability of sintered Nd-Fe-B magnets with holmium substitution

Jinghui Di^1,2,3，Shuai Guo^1,2，Ling Chen^1,2，Guangfei Ding^1,2，Kan Chen^1,2，Ming Li^1,2，Don Lee⁵，Aru Yan^1,2

1. Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences2. Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences3. University of Chinese Academy of Sciences5. University of Dayton

摘 要：The effects of Ho substitution for Nd on the microstructure, corrosion resistance and thermal stability of the Nd-Fe-B magnets were investigated. The（Nd,Ho）-O phase was formed with increasing Ho substitution. The results of potentiodynamic polarization and highly accelerated stress test show improved corrosion resistance with increasing Ho substitution. The optimum mass loss 0.29 mg/cm² is achieved.Moreover, the average temperature coefficients for remanence and coercivity in the range of 25-150℃are both closer to zero, indicating improved thermal stability. The mechanisms for the improved corrosion resistance and thermal stability are discussed in relation to the microstructure featuring the（Nd,Ho）-O phase.

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