Title :
High coercivity in boron substituted Sm-Co melt-spun magnets
Author :
Makridis, Sofoklis S. ; Litsardakis, George ; Panagiotopoulos, Ioannis ; Niarchos, Dimitrios ; Zhang, Yong ; Hadjipanayis, George C.
Author_Institution :
Dept. of Electr. & Comput. Eng., Thessaloniki Univ., Greece
fDate :
9/1/2002 12:00:00 AM
Abstract :
The structural and magnetic properties of nanocomposite melt-spun Sm(Co0.74-xFe0.1Cu0.12Zr0.04Bx)7.5 magnets have been investigated as a function of boron content (x = 0.005 0.05), wheel speed and annealing conditions. The as-spun ribbons are nanocrystalline with fine microstructure and average grain size of 60-100 nm. X-ray diffraction indicates that the as-spun samples have the metastable hexagonal TbCu7-type structure phase and fcc-Co as a secondary soft phase. Magnetization at nonsaturating 5 T field is 45-72 emu/g and the reduced remanence (Mr/Ms) is above 0.8. The loop shape exhibits a characteristic step due to the soft magnetic phase. At room temperature, Hc values of 20-28 kOe are obtained for as spun samples, with a record value of 38.5 kOe for x = 0.04. At 380°C Hc values higher than 5 kOe are observed. Coercivity and loop shape are strongly dependent on annealing conditions.
Keywords :
X-ray diffraction; annealing; boron alloys; cobalt alloys; coercive force; ferromagnetic materials; grain size; magnetic hysteresis; magnetisation; melt spinning; nanostructured materials; permanent magnets; remanence; samarium alloys; 380 degC; 5 T; Sm((CoB)0.74Fe0.1Cu0.12Zr0.04)7.5; X-ray diffraction; annealing; boron substituted Sm-Co nanocomposite; coercivity; grain size; hard magnetic material; magnetic hysteresis loop shape; magnetic properties; magnetization; melt spinning; microstructure; permanent magnet; remanence; structural properties; Annealing; Boron; Coercive force; Iron; Magnetic properties; Magnets; Microstructure; Shape; Wheels; Zirconium;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2002.803068
