Gd substitution for Ce in preparing (Ce,Gd)-Fe-B magnets

Abstract

Ce-Fe-B rare-earth alloys are alternative to substitute partially for Nd-Fe-B permanent magnets for reducing the cost and the balance use of rare-earth elements. However, coercivity is rather low in Ce-Fe-B magnets, which partially ascribes to the instability of Ce2Fe14B phase and the low magnetocrystalline anisotropy. In this paper, magnetic properties are investigated in Ce13-xGdxFe81B6 ribbons via substituting of Gd for Ce. X-ray diffraction shows that a little amount of Gd substitution for Ce leads to an increase in the intensity of diffraction peak for main phase, which should be attributed to the improvement of the stability of R2Fe14B phase and the reduction in the amount of amorphous phase. Even though the magnetocrystalline anisotropy is lower in Gd2Fe14B than that in Ce2Fe14B, the coercivity increases to 5.88 kOe for a little amount of Gd substitution in Ce12Gd1Fe81B6 ribbons. For Gd atomic percent more than 3% the coercivity decreases, and the remanence drops significantly. With the increase of Gd atomic percent, Curie temperature increases monotonically. Henkel plots indicate that Gd substitution for Ce could enhance the effect of exchange coupling, which owes to the increase of exchange coefficient in main phase as well as to the reduction in the amount of amorphous phase. These investigations show that a little amount substitution of Gd is beneficial to improve the magnetic properties without a significant drop of the remanence.