Magnetic properties, phase transition temperatures and microstructure of CeFeB-alnico ribbons

Alnico 8 elements are added into Ce-Fe-B ribbons and the effects of the multi elements on the magnetic properties, phase transition temperatures and microstructure are investigated. It is found that the addition of alnico elements is helpful for enhancing the magnetic properties of the Ce-Fe-B alloys. The Curie temperature of Ce₂Fe₁₄B (2:14:1) main phase increased from 422 K for the standard alloy to 490 K by 20 wt% addition of alnico, while the Curie temperature of CeFe₂ (1:2) phase decreased from 223 K to 122 K. The transmission electron microscopy (TEM) analysis showed that the nano grains of the alloys are refined which is attributed to the refractory character of Ti. The intergranular exchange interactions measured by applying Henkel plots also enhanced by adding alnico elements into Ce-Fe-B ribbons. The magnetic properties H_cj, B_r and (BH)_max improved significantly for the optimized addition of alnico. Magnetic properties of H_cj = 5.16 kOe, B_r = 4.59 kG and (BH)_max = 4.14 MGOe are obtained in Ce₃₅Fe_56.5(alnico)_7.5B ribbon. The improved magnetic properties in alnico-doped Ce-Fe-B alloys are attributed to the refined microstructure and enhanced intergranular exchange interactions.