Structure and magnetic properties of Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 melt-spun

M. Gjoka, et al., Mater. Sci. Eng. B (2008), doi:10.1016/j.mseb.2008.06.003

Structure and magnetic properties of Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 melt-spun
nanostructured alloys

M. Gjoka, D. Niarchos, K. Giannakopoulos, C. Sarafidis, O. Kalogirou, M. Grigoras,
N. Lupu, H. Chiriac


a b s t r a c t
Melt-spun ribbons with a composition of Sm (Co0.74Fe0.1Cu0.12Zr0.04)8 were prepared with a wheel speed of 40 m/s, followed by vacuum heat treatment in the temperature range of 650–850 ◦C, for different durations. X-raypowderdiffraction (XRD) results showedthat themainphase is ofTbCu7-type for both, as-spun and annealed ribbons, except a small amount of -Fe(Co). The intrinsic coercivity values iHc = 6.9 kOe for the sample heat treated at 700 ◦C for 35 min. When the annealing time is increased more than 30 min, the coercivity decreases and a third phase appears. The microstructure of the ribbon samples was characterised by using scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDAX).
Detailed results for the microstructure in Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 melt-spun ribbons and the correlation between the magnetic properties and the grains size are presented.


Recently, precipitation-hardened Sm(Co,Fe,Cu,Zr)z (z = 7.0–8.5) nanophase magnets have again received considerable atten- tion due to the further increase in operating temperature and potentially high (BH)max values. Among the preparation techniques, the melt-spinning rapid solidification method has been used successfully to fabricate nanophase magnets. Some inves- tigations have been performed on melt-spun ribbons of the Sm(Co,Cu,Fe,Zr)y (y = 7.0–8.5) system. Detailed results of the effect of Zr addition in Sm(Co0.68−xFe0.25Cu0.07Zrx)7.7 melt-
spun ribbons (v = 45m/s) have been reported [1]. Rapidly quenched Sm(CobalCu0.08Fe0.22Zr0.02)8.5 (Cu-/Fe-rich) and
Sm(CobalCu0.05Fe0.10Zr0.03)8.5 (Cu-/Fe-poor) ribbons (v=30m/s)
have been prepared by means of the melt-spinning tech-nique [2]. The effect of alloy composition, the temperature range of cooling regime on microstructure, coercivity and 31
dependence on the isothermal aging time and magnetic properties of melt-spun Sm(Co0.74Fe0.1Cu0.12Zr0.04)7.5 (Cu/Zr-rich)
and Sm(Co0.75Fe0.15Cu0.08Zr0.02)7.6 (Cu/Zr-poor) magnets have been investigated [3–9]. All those ribbons are produced with been studied for the Sm(CobalFe0.1CuxZr0.03)7 (x = 0.0–0.25) (5 m/s) ribbons [10]. In this work we report the effect of alloy
composition and aging time on microstructure and magnetic
properties of melt-spun Sm(Co0.74Fe0.1Cu0.12Zr0.04)8 Cu/Zr-rich) produced in slightly different conditions from the previous
reports.