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

The effect of Fe, Cu, Zr, and Ti substitution on magnetic properties of SmCo 1:7 magnets at temperatures up to 500°C were studied. As-milled amorphous Sm(Co,Fe,Cu,Ti-Zr)7 magnets crystallized in the TbCu7-type structure after annealing at 750°C for 2 h. A room-temperature intrinsic coercivity of around 2.5 T is obtained for compositions SmCo6.4 Zr0.2 Ti0.4 and SmCo6.4 Fe0.1 Zr0.1 Ti0.4. The high coercivity of the ball-milled SmCo7-x Tix magnets is attributed to the strong pinning of the walls of the "interaction domains" by the network of grain boundaries between the nanocrystalline grains. The virgin curve of the ball-milled samples is suggestive of strong domain wall pinning.