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S.S. Makridis, G. Litsardakis, K.G. Efthimiadis, S. Höfinger, J. Fidler, D. Niarchos:
"Sm(Co, Fe, Cu, Zr, C)_8.2 ribbons for high-temperature magnets";
Journal of Magnetism and Magnetic Materials, 272-276 (2004), Suppl. 1; E1921 - E1923.

Sm(Co, Fe, Cu, Zr, C)_8.2 ribbons for high-temperature magnets

Sofoklis S. Makridis a, d, George Litsardakis, a,
K.G.Kostas G. Efthimiadis b, Sabine Höfinger c, Josef Fidler c and Dimitris Niarchos d

a Department of Electrical & Computer Engineering, Aristotle University, GR-54124, Thessaloniki, Greece
b Department of Physics, Aristotle University, Thessaloniki, 54124, Greece
c Institute of Applied and Technical Physics, Vienna University of Technology, A-1040, Vienna, Austria
d Institute of Materials Science, NCSR "Demokritos", 15310, Athens, Greece

Available online 5 February 2004.

Abstract

The effect of carbon substitution for cobalt on the structure and magnetic properties at room and high temperature of melt spun ribbons with composition Sm(Co_0.86-xFe_0.1Zr_0.04C_x)_8.2 and Sm(Co_0.74-xFe_0.1Cu_0.12Zr_0.04C_x)_8.2 (x=0-0.015) has been studied. Arc-melted bulk samples have Th₂Ni₁₇-type structure while ribbons have TbCu₇-type structure. Average grain size for Cu-free sample with x=0.005 is 23 nm while for Cu-doped samples it varies from 53 to 22 nm when x varies from 0.005 to 0.015, respectively. Coercive as-spun samples have H_c~2.2-7.8 kOe and reduced remanence mr=M_r/M_s up to 0.74. Ribbons of the Cu-free composition with x=0 and 0.005 and annealed at 750°C for 1 h have TbCu₇-type structure with coercivity values 4.9 and 3.0 kOe respectively, while for x=0.01 and 0.015, FCC-Co is the dominant phase. Cu-doped ribbons with x=0.005, after annealing at 750°C for 2 h, are characterized at room temperature by square hysteresis loop with H_c=8.3 kOe, reduced remanence m_r=0.75 and (BH)_max=6.3 MGOe. Loops at higher temperatures are also square with high m_r; for x=0.01 the magnetization is 89 emu/g and the coercive field is 1.8 kOe at 400°C.

Author Keywords: Coercivity; High-temperature permanent magnets; Rare-earth permanent magnets

75.60.Ej; 75.50.Ww

http://dx.doi.org/10.1016/j.jmmm.2003.12.457