Dual enhancement mechanism for grain boundary optimization and magnetic properties in Ce magnets: The critical role of Ga/Cu in PrFe-based alloys (PrFe, PrFeGa, PrFeCuGa)

To counteract the adverse effects of Ce element on the magnetic properties of NdFeB magnets, this research utilizes a grain boundary addition technique with low-melting-point PrFe-based alloy, achieving successful fabrication of magnets exhibiting dual enhancement in both remanence and coercivity. The experimental results showed that the PFG (PrFeGa) magnet exhibited an increase in coercivity from 11.45 kOe (original magnet) to 14.25 kOe with a slight improvement in remanence, while the PFCG(PrFeCuGa) magnet achieved a remanence increase of 0.52 kGs and a coercivity enhancement of 2.49 kOe. The introduction of the PrFe-based alloy optimized the grain boundary phase ratio, distribution uniformity, and fluidity, while enhancing the alignment consistency of the main phase and the proportion of Ce³⁺ ions within its unit cells, thereby promoting the improvement of both remanence and coercivity in the magnet. First-principles calculations of formation energy demonstrate that in PFG magnets, Ga promotes the formation of antiferromagnetic 6:13:1 phase to weaken main-phase magnetic exchange coupling and enhance coercivity, while in PFCG magnets, Cu suppresses 6:13:1 phase formation but excess RE and Fe elements form Pr-rich regenerated main phase between the main phase and RE-rich phase, significantly improving remanence through increased main-phase proportion.