Elevated temperature behavior of rapidly quenched La/Ce substituted nanocrystalline NdFeB alloys with various compositions

Abstract

Here we report the elevated temperature behaviors of rapidly quenched La/Ce substituted nanocrystalline NdFeB alloys with a wide range of compositions, including nano-composites of (Nd0.8Ce0.2)10Fe84B6, (Nd0.9La0.1)10Fe84B6, [Nd0.7(La0.5Ce0.5)0.3]10Fe84B6 and [Dy0.7(La0.5Ce0.5)0.3]10Fe84B6, single phase alloys of (Nd0.95La0.05)12Fe82B6 and (Nd0.8Ce0.2)12Fe82B6, as well as Co substituted single phase [Nd0.7(La0.5Ce0.5)0.3]12Fe72Co10B6 and RE-rich phase [Nd0.7(La0.5Ce0.5)0.3]14Fe70Co10B6 alloys. All compositions were fabricated by melt spinning technique. For nanocomposite alloys, the optimum high temperature magnetic properties at 400 K including remanent magnetization (Mr), maximum energy product (BH)max and coercivity (Hc) up to 89 emu/g, 65 kJ/m3, 226 kA/m, respectively, for Ce-substituted alloy and 70 emu/g, 46 kJ/m3 and 246 kA/m, respectively, for La-substituted alloys have been obtained. The decrease of Hc is ascribed to the microstructure sensitivity of La/Ce substituted NdFeB nanocomposite alloys at higher temperature. For single phase alloys, the optimum magnetic properties such as Mr, (BH)max and Hc up to 81 emu/g, 67 kJ/m3, 412 kA/m and 77 emu/g, 53 kJ/m3 and 349 kA/m have been obtained for La-substituted and Ce-substituted alloys at 400 K, respectively. The Ce-substituted alloys are relatively more sensitive to the elevated temperature compared to La-substituted alloys for both composites and single phase alloys. Substitution of 10% Co for Fe in both single phase and RE-rich phase alloys leads to the excellent elevated temperature magnetic properties at 400 K. The existing results state that La, Ce or LaCe substitutions for Nd and partial substitution of Co for Fe maintain a rather good combination of improved Curie temperature and elevated temperature magnetic properties at or above 400 K in all alloys with various phase constitutions.