The Structure And Magnetic Properties Of Sm(Co,M)₇-Type (M=Ti,Hf,Cu) Ribbons

Sm-Co based intermetallic compounds with the TbCu7-type structure have been widely studieddue to their perfect intrinsic magnetic properties such as high Curie temperature and highanisotropy field.In this paper, Ti, Cu and Hf were added into the Sm-Co based permanent magnetic alloy inorder to stabilize the Sm(Co,M)7 phase with the TbCu7-type structure. SmCo6.6Ti0.4,SmCo6.6Ti0.4(CNTs)0.05, SmCo_6.6Ti_0.4C_0.05, SmCo_6.9Hf_0.1C_0.02(CNTs)_0.03, SmCo_7-xCu_x (x=0.8, 1.5,3.5) with TbCu7-type structure have been prepared by melt-spinning method. The phasecomposition, microsturcture and magnetic properties of as-cast alloys and as-spun ribbons wereinvestigated using X-ray diffractometer, Scanning Electronic Microscopy and Vibrating SampleMagnetometer.It was found that Ti, Cu and Hf were beneficial for stabilizing the metastable 1:7 phase andincreasing the magnetic anisotropy of Sm(Co,M)7 phase. The C and CNTs additions led to areduction in grain size, while the effect of CNTs is more obviously. The grain size was reducedeffectively and the 1:7 phase was stabilized significantly by melt-spinning technology.SmCo_6.9Hf_0.1C_0.02(CNTs)_0.03 ribbons melt-spun at optimum speed of 40 m/s, have the bestcomprehensive magnetic properties: Hci=10628.Oe, Mr=44.1emu/g, M_s2T=62.8emu/g,Mr/Ms2T=0.7. Cu is also beneficial to improve the orientation degree and increase the anisotropyfield of as-cast SmCo_7-xCu_x alloys, the optimal magnetic properties of Hci=12703.7Oe,Mr=25.1emu/g, Mr/M_s2T=0.825 were achieved in as-cast SmCo_3.5Cu_3.5 alloy. Except for SmCo7-xCux alloys, the magnetic properties of other Sm-Co-M (M=Ti, Hf) ribbons were better than thecorresponding as-cast alloys.