Understanding the composition effects on the hot-deformed Nd-Fe-B magnets based on two different melt spun powders

摘要

The properties of RE-rich phase have important effects on the process and magnetic properties of NdFeB magnets. In this work, two MQ powders with different compositions were employed to fabricate hot pressed and hot-deformed magnets. The hot-deformed magnets produced from MQP-01 powders with Pr containing and Zr/Nb-free composition exhibit lower coercivity and less pinning effect compared to those from MQP-02 powders with Pr-free and Zr/Nb-containing composition, though the former has high rare earth (RE) content. These differences are attributed to the different mobilities of the RE-rich phase in the grain boundaries due to the composition difference. The RE-rich phase in MQP-01 powders has relatively good mobility, which leads to the aggregation of RE-rich phase and the open recoil loops for deformed magnets. On the contrary, relatively poor mobility of RE-rich phase in MQP-02 powders results in the thick and continuously distributed grain boundary phase in the hot-deformed magnets, which contributes to the strong pining effect and the high coercivity. The present results provide reference for optimizing the magnetic properties of hot deformed NdFeB type magnets.

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