Tunning Ce valence and optimizing intergranular phase to prepare high abundance (La, Ce, Pr)-Fe-B permanent alloys with excellent properties

Abstract

The regulation of Ce valence and the optimization of intergranular phase can effectively improve magnetic properties, which is beneficial in promoting the application of high abundance rare earth in permanent magnets. In this work, [(La0.3Ce0.7)xPr1-x]17Fe78B6 (x = 0.1–0.7) melt-spun alloys are prepared. The results illustrate that, Ce shows the mixed valency consisting of Ce3+ and Ce4+ configuration, and when x = 0.3, the alloy possesses the highest Ce3+ ratio. Meanwhile, the highest Ce4+ ratio can be determined in x = 0.1 alloy. TEM characterization demonstrates that, the intergranular rare earth oxides including CeO2 phase, Pr2O3 phase, (Pr, Ce)2O3 as well as La2O3 phase can be determined, among which CeO2 phase, existed in x = 0.3 alloy, is more beneficial in elevating the coercivity. Thus, the optimum comprehensive magnetic properties with the remanence of 6.5 kG and the coercivity of 14.9 kOe can be obtained in x = 0.3 alloy. In addition, due to more uniform microstructure of melt-spun alloy with x = 0.3, higher thermal stability can be obtained. Elemental metallurgical behavior reveals that La, Ce and Pr elements are enriched in intergranular phase, and main phase region is rich for Fe element.