Synchronous enhancement mechanism of magnetic property for dual-main-phase Ce magnets by grain boundary diffusion with Pr-Al alloy

The Pr80Al20 (at%) alloy was diffused into the dual-main-phase Ce magnets (Ce/TRE = 40 wt.%, TRE: total rare earth) with different diffusion time by grain boundary diffusion process (GBDP). The magnetic property and the microstructure of a series of magnets with different diffusion time were investigated. The coercivity gradually increased as the diffusion time increased, while the remanence remained basically constant. The improvement of coercivity originated from the synergistic contribution of modified grain boundaries with decoupling effect and Ce-rich main phase containing Pr with improved magnetocrystalline anisotropy. The percentage of the irreversible portion and the nucleation field of the reverse domain calculated from recoil loops curves further confirmed that the diffusion of Pr80Al20 alloy enhanced the coercivity. The enhanced anisotropy of the Ce-rich grains compensates for the decay of the remanence carried by the diffusion-induced increase in the nonmagnetic grain boundary phase, which ultimately results in the remanence remaining essentially constant. The above phenomena further broaden the room-temperature applications of dual-main-phase magnets with high Ce content without heavy rare-earth grain boundary diffusion. •Dual-main-phase magnets with high Ce content were diffused with light rare earth Pr-Al alloy.•Pr element mapping contrast clearly indicated sufficient diffusion inside the magnet.•Small amounts of Pr entered into the Ce-rich main phase grains to improve magnetocrystalline anisotropy.•Synchronous enhancement mechanism in coercivity and maximum energy product of the magnets was revealed.