  High coercivity, the highest for Cu-free 2 : 17 Sm-Co ribbons, has been
obtained in as-spun (= 211 kOe) and short time annealed (= 232 kOe) samples of
Sm(CobalFe Zr B)7 5 alloys, with varying B, Zr, and Fe content (= 0-0 06, = 0-0
16, = 0 08-0 3) and wheel speed. In as-spun samples, the TbCu7 type structure
and in annealed samples the Th2Zn17 and CaCu5 type structures is observed, plus
fcc Co as minority phase is observed. Reduced remanence () is higher than 0.7.
High-temperature magnetic measurements show very good stability above 300 C
with coercive field as high as 5.2 kOe at 330 C. For annealed Sm(CobalFe0 3Zr0
02B0 04)7 5, very good loop squareness and high maximum energy product of 10.7
MGOe have been obtained. Increasing Zr content results in less uniform
microstructure of annealed ribbons.
