Nanostructured melt-spun Sm(Co,Fe,Zr,B)/sub 7.5/ alloys for high-temperature magnets

High coercivity, the highest for Cu-free 2 : 17 Sm-Co ribbons, has been obtained in as-spun (H/sub c/=21.1 kOe) and short time annealed (H/sub c/=23.2 kOe) samples of Sm(Co/sub bal/Fe/sub z/Zr/sub y/B/sub x/)/sub 7.5/ alloys, with varying B, Zr, and Fe content (x = 0-0.06, y=00.16, z = 0.08-0.3) and wheel speed. In as-spun samples, the TbCu/sub 7/ type structure and in annealed samples the Th/sub 2/Zn/sub 17/ and CaCu/sub 5/ type structures is observed, plus fcc Co as minority phase is observed. Reduced remanence (M/sub r//M/sub s/) is higher than 0.7. High-temperature magnetic measurements show very good stability above 300(degree)C with coercive field as high as 5.2 kOe at 330(degree)C. For annealed Sm(Co/sub bal/Fe/sub 0.3/Zr/sub 0.02/B/sub 0.04/)/sub 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.