Performance improvement and element segregation behavior in Y substituted nanocrystalline (La,Ce)-Fe-B permanent magnetic alloys without critical RE elements

Developing Ce, La, or Y based rare earth (RE) permanent magnets is a practical way to balance the utilization of RE resources. In this work, Y substitution for Ce and La is found to not only enhance the hard magnetic properties, but also significantly increase the Curie temperature T-c and thermal stability of the melt-spun (Ce0.7La0.3)(2)Fe14B alloys. To further optimize the magnetic performance, the RE-rich alloy with [(Ce0.7La0.3)(0.8)Y-0.2](17)Fe78B6 composition has been prepared. The good combination of magnetic properties with maximum energy product (BH)(max) = 7.1 MGOe, intrinsic coercivity H-cj = 357 kA/m, and remanent polarization J(r) = 0.70 T has been obtained, together with low temperature coefficients of remanence (alpha = -0.255%/K) and coercivity (beta = -0.246%/K). Importantly, RE element segregation has been confirmed in RE-rich (Ce,La,Y)-Fe-B alloys by microstructure and composition analysis. La prefers to enter into the intergranular phase than Ce and Y prefers to remain in the hard magnetic main phase, which results in increased T-c, improved magnetic properties, and enhanced thermal stability. (C) 2020 Elsevier B.V. All rights reserved.