PHASE EVOLUTION AND MAGNETIC PROPERTIES OF TbCu7-TYPE (Sm, Pr)Co7-xHfxMy (x = 0-0.5; y = 0-0.14) RIBBONS

Abstract

The effects of Hf substitution and C content on the magnetic properties, phase evolution, and microstructure of melt spun ( Sm , Pr ) Co 7- x Hf x C y ( x = 0-0.5; y = 0-0.14) ribbons have been studied. A proper Hf substitution is helpful not only in stabilizing 1:7 phase but also in enhancing its magnetic anisotropy field. As a result, magnetic properties of B r = 6.4 kG , i H c = 7.3 kOe and ( BH ) max = 8.7 MGOe for SmCo 6.9 Hf 0.1 ribbons are obtained. Besides, a small amount of C addition in the ribbons could slightly modify phase constitution and effectively refine their microstructure to strengthen the exchange coupling effect between magnetic grains. Furthermore, a slight Pr substitution for Sm may further increase the magnetization and the magnetic properties of the ribbons. The optimal magnetic properties of B r = 7.1 kG , i H c = 8.5 kOe and ( BH ) max = 11.2 MGOe could be achieved for the directly quenched Sm 0.8 Pr 0.2 Co 6.9 Hf 0.1 C 0.12 ribbons.