journal article·2024-08

Improvement of magnetic performance of Nd-Ce-Fe-B sintered magnets via Pr-Co-Ga grain boundary reconstruction

Rongshun Lai, Qiang Ma, Haibo Xu, Zhibin Li, Baogen Shen

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Abstract

Grain boundary reconstruction is a commonly used method to improve the coercivity of Nd-Ce-Fe-B magnets but at the expense of a notable reduction in remanence. In this study, we present an effective approach to achieving a balance between remanence and coercivity of Nd-Ce-Fe-B magnets through Pr-Co-Ga grain boundary reconstruction. Compared to the original Nd 0.7-Ce 0.3 -Fe-B magnet, the remanence of the magnet with 4 wt% Pr-Co-Ga addition decreased only from 13.09 kGs to 12.8 kGs, while the coercivity remarkably increased from 10.95 kOe to 14.84 kOe. Additionally, the coercivity temperature coefficient (20–150 °C) was improved from − 0.606 %/°C to − 0.547 %/°C, and the Curie temperature was increased from 278.4 °C to 285.1 °C, demonstrating excellent thermal stability. XRD refinement analysis showed a slight decrease in the main phase ratio, accompanied by a slight increase in orientation, resulting in a slight decrease in remanence. SEM and EPMA observations revealed that Pr preferentially replaced Ce on the grain surface, forming a “Pr-rich” shell with an enhanced anisotropy field. TEM analysis showed that the magnets with PCG addition exhibit a continuous Fe-lean grain boundary phase, weakening the exchange coupling of the adjacent grains. The synergistic effect of the “Pr-rich” shell formation and grain boundary optimization effectively enhanced the coercivity.
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Research context

OpenAlex topics: Magnetic Properties of Alloys · Magnetic Properties and Applications · Magnetic properties of thin films

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

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