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Developing permanent magnets based on full high abundance rare-earth (RE) elements of Ce, La, and Y offers tremendous potential for the balanced utilization of RE resources, but the magnetic properties of these magnets are restricted due to the magnetic dilution caused by the existence of the paramagnetic REFe2 laves phase. Herein, the non-RE element Ge with high efficiency was introduced to enhance the magnetic performance of Ce-, La-, and Y-based RE–Fe–B nanocrystalline alloys, and the highest maximum energy product [(BH)max] of 65.6 kJ/m3 and an enhanced coercivity (Hcj) of 346 kA/m were achieved in the [(Ce0.8La0.2)0.5Y0.5]16Fe77.5B6Ge0.5 alloy. This improvement is attributed to the increased content of the hard magnetic RE2Fe14B phase with refined grain size, which is further confirmed by micromagnetic simulation. First-principles calculations and a microstructure analysis reveal that the laves phase is effectively suppressed by Ge addition due to the formation of the Ce5Ge3 phase with the lowest formation energy. This work clarifies the positive role of Ge in simultaneously enhancing the Hci and (BH)max of nanostructured (Ce,La,Y)–Fe–B alloys. [ABSTRACT FROM AUTHOR]

Considering that both La2Fe14B and Ce2Fe14B compounds exhibit similar weak temperature-dependent anisotropic fields (HA) as Y2Fe14B, this work aims to clarify the elevated temperature behavior of melt-spun nanocrystalline La- or Ce-partially substituted stoichiometric Y2Fe14B alloys containing no critical rare earth elements. The results show that La-substituted (Y1−xLax)2Fe14B alloys (x = 0–0.5) show exceptional elevated temperature behavior, manifested by the increased coercivity with increasing temperature. For the Ce-substituted (Y1−xCex)2Fe14B alloys, only x = 0.1 and 0.2 alloys show the similar trend. Both the temperature coefficient of remanence α and coercivity β can be improved by La-substituted, indicating partial substitution La can effectively enhance the thermal stability of Y2Fe14B alloy. However, excess La or Ce substitution would reduce α and β value, resulting in the deterioration of thermal stability. Highest β values of 0.05 and − 0.08 have been obtained in (Y0.9La0.1)2Fe14B alloy at 300–400 K and (Y0.8La0.2)2Fe14B alloy at 300–500 K, respectively. In addition, Ce substitution can effectively enhance the coercivity of Y2Fe14B alloy at room temperature and La substitution does not show a beneficial effect on the room-temperature magnetic properties. This work is beneficial for developing high-performance/cost ratio permanent magnets based on abundant rare earth elements with superior thermal stability. [ABSTRACT FROM AUTHOR]

• The formation of undesired CeFe 2 phase is suppressed by La substitution. • La aggregates in intergranular phase and forms La-rich phase. • Combining La-substitution and Si-addition helps to save coercivity. • (BH) max = 6.5 MGOe was obtained by using 40 at.% La-substitution and Si-addition. • Smallest | β |=0.324 %/℃ was also obtained in (Ce 0.6 La 0.4) 17 Fe 75 Si 3 B 6 alloy. To balance the utilization of rare-earth resource, Ce and La have been proposed to be employed in RE 2 Fe 14 B-type magnetic materials to produce fully high abundance rare-earth magnets. In this work, the effects of La on the phase constitution, microstructure and magnetic properties of melt spun (Ce 1-x La x) 17 Fe 78 B 6 alloys and (Ce 1-y La y) 17 Fe 75 Si 3 B 6 alloys have been systematically investigated. La effectively inhibits the formation of CeFe 2 phase and increases the volume fraction of 2:14:1 phase. The TEM results indicate that La prefers to enter into intergranular phase and form bulk aggregations. La-substitution improves the remanence J r , the maximum energy product (BH) max , curie temperature T c and thermal stability, but reduces the coercivity H c. Si modified (Ce 1-y La y) 17 Fe 75 Si 3 B 6 alloys exhibit better demagnetization curve squareness and superior magnetic properties than (Ce 1-x La x) 17 Fe 78 B 6 alloys due to the refined microstructure. In addition, Si-doped alloys show better thermal stability due to the enhanced curie temperature T c. The results indicate that higher La content can be employed in Si doped Ce-Fe-B-based alloys for improved properties. The best combination of magnetic properties with (BH) max = 6.5 MGOe, H c = 336 kA/m, J r = 0.60 T and coercivity coefficient | β |=0.324 %/℃ is obtained in (Ce 0.6 La 0.4) 17 Fe 75 Si 3 B 6 alloy. The current work suggests that Ce-La-Fe-B alloys are potential to fabricate the so-called 'Gap Magnets', however, the composition modification is also required in order to improve their performance. [ABSTRACT FROM AUTHOR]

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 (Ce 0.7 La 0.3) 2 Fe 14 B alloys. To further optimize the magnetic performance, the RE-rich alloy with [(Ce 0.7 La 0.3) 0.8 Y 0.2 17 Fe 78 B 6 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 (α = −0.255%/K) and coercivity (β = −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. • A new high-abundance Ce/La/Y-based permanent magnets have been developed. • A good combination of magnetic properties can be obtained in (Ce,La,Y)–Fe–B alloys. • RE element segregation has been confirmed in RE-rich (Ce,La,Y)–Fe–B alloys. • La element prefers to enter into the intergranular phase than Ce element. • Y element likes to remain in the hard magnetic 2:14:1 phase. [ABSTRACT FROM AUTHOR]

• (La,Y) 2 Fe 14 B alloys with various La/Y ratios are prepared by melt spinning. • Formation of La 2 Fe 14 B phase in La-Fe-B alloys can be enhanced by Y substitution. • Over 30% Y substitution is needed to obtain preferable hard magnetic properties. • Y-substitution can enhance inter-grain exchange coupling and corrosion resistance. • (La,Y) 2 Fe 14 B alloys show better corrosion resistance than Nd 2 Fe 14 B alloy. Aiming to develop the rare earth-iron-boron permanent magnets with high performance/cost ratio, a systematic investigation on the phase structure, microstructure, magnetic properties, and corrosion resistance of melt-spun nanocrystalline (La 1−x Y x) 2 Fe 14 B alloys has been carried out. In La based alloys, at least 20 at% Y substitution for La is needed to form hard magnetic 2:14:1 phase. With the increase of Y content, the lattice parameters a , c of 2:14:1 phase decrease and its Curie temperature T c increases linearly. Y substitution also can effectively enhance the inter-grain exchange coupling and the corrosion resistance of La 2 Fe 14 B alloy. The corrosion current density i corr decreases from 36.2 μA/cm2 to 10.6 μA/cm2 in 3.5 wt% NaCl solution with increasing x from 0.2 to 1.0, and all these values are lower than those for nanocrystalline Nd 2 Fe 14 B alloy. The hard magnetic properties with maximum energy product (BH) max of 2.6 MGOe, remanent polarization J r of 0.65 T, and intrinsic coercivity H cj of 84 kA/m have been obtained in (La 0.7 Y 0.3) 2 Fe 14 B alloys. Y 2 Fe 14 B alloy shows the highest (BH) max of 6.8 MGOe, J r of 0.88 T, and H cj of 148 kA/m. This work suggests that La-Y-Fe-B alloys also have the potential for fabricating new and low-cost magnetic materials with performance better than hard ferrites. [ABSTRACT FROM AUTHOR]