Effect of Fe, Cu, Zr, and Ti on the magnetic properties of SmCo-1:7 magnets

Abstract

Summary form only given. Nanocrystalline Sm-Co-Cu-Ti magnets prepared by mechanical milling and subsequent annealing were reported to exhibit excellent room temperature coercivity. In this study, investigations of the effects of Fe, Cu, Zr and Ti substitution on magnetic properties of 1:7 magnets at temperatures up to 450/spl deg/C were investigated. The alloys with nominal composition SmCo/sub 6.6-x/(Fe/Zr)/sub x/Ti/sub 0.4/ (x = 0.0, 0.1 and 0.2) and SmCo/sub 6.8-x/Ti/sub x/Cu/sub 0.1/Fe/sub 0.1/ (x = 0.2, 0.3, 0.4) were prepared by arc melting in a high purity argon atmosphere. The alloy ingots were then crushed and milled for 12 h using high energy ball mill. The as-milled powders were annealed at 750/spl deg/C for 2 hours. X-ray diffraction confirms the formation of TbCu/sub 7/-type structure with minor amounts of the Tb/sub 2/Zn/sub 17/ rhombohedral phase. Grain size is /spl ap/ 40 nm. The authors show the room temperature hysteresis loops of ball-milled SmCo-1:7 compositions with Fe and Zr doping. All compounds exhibit room temperature coercivity of more than 1 T. Substitution of Zr and Ti increases the room temperature coercivity whereas Fe substitution leads to an decrease of the magnetization but a decrease of the coercivity. A room temperature intrinsic coercivity of around 2.5 T is obtained for compositions SmCo/sub 6.4/Zr/sub 0.2/Ti/sub 0.4/ and SmCo/sub 6.4/Fe/sub 0.1/Zr/sub 0.1/Ti/sub 0.4/.