Structure and magnetic properties of Sm(Co/sub bal/Fe/sub x/Zr/sub 0.05/Cu/sub 0.08/Ga/sub y/B/sub z/)/sub 12/ alloys

3d-rich alloys and their melt-spun materials with nominal compositions of Sm(Co/sub bal/Fe/sub x/Zr/sub 0.05/Cu/sub 0.08/Ga/sub y/B/sub z/)/sub 12/ (x=0.1-0.41, y=0-0.01, z=0.01-0.02) were synthesized and characterized in the temperature range of 10-1473 K and at fields up to 5 T. The main phase of the as-cast alloys was formed in a Th/sub 2/Ni/sub 17/ type structure, exhibiting a strong uniaxial anisotropy. As a result, encouraging hard magnetic properties with T/sub c/=995-1086 K, H/sub a/=40-115 kOe, M/sub s/=10-12.8 kG at 300 K, and H/sub a/=60-180 kOe, M/sub s/=10.4-13.6 kG at 10 K were observed in the as-cast alloys. The melt-spun materials are nano-structured in nature and magnetically hard, even in the as-spun state. The following hard magnetic properties were observed: H/sub ci/=7-10 kOe, 4(pi)M/sub s/=9.4-11.7 kG, at 300 K, and H/sub ci/=17-27 kOe, 4(pi)M/sub s/=9.6-12.1 kG, at 10 K. The highest (BH)/sub max/~9.8 MGOe at 300 K was obtained from the Sm(Co/sub bal/Fe/sub 0.31/Zr/sub 0.05/Cu/sub 0.08/B/sub 0.02/)/sub 12/ ribbon material. A Henkel plot analysis indicates the existence of a strong exchange-coupling interaction between the magnetically hard and soft phases in these ribbon materials. The effects of adding Ga, B, and Fe on the magnetic properties will be discussed.