Coercivity of bulk anisotropic nanocomposite Sm(CoFeTi)8–10 magnets

The present study investigates the effects of nonmagnetic metal additions on Sm(CobalFe0.2Ti0.05MxB0.01)z (x=0–0.04 and z=8–10) based melt-spun alloys. M=Nb, Ga, Cu, and Al were selected to form anisotropic nanocomposite bulk magnets via hot pressing followed by a hot deformation. The effects of Nb, Ga, Cu, and Al substitutions on intrinsic coercivity Hci and possible mechanisms behind the improvement in Hci, such as phase formations, anisotropy field HA, and microstructure were investigated. Experimental results indicated an over 20%–50% enhancement in Hci after hot deformation (HD) with Nb, Ga, and Cu additions for magnets with z=8 and z=10. Especially with the Nb addition, the Hci improved from 8.7 to 12 kOe for the z=8 magnet, and from 5 to 11 kOe for the z=10 magnet. An unusual enhancement in Hci, from 9 kOe after hot pressing (HP) at 700 °C to 11 kOe after HD at 850 °C, was observed in the Nb-doped magnet with z=10. Our analysis on possible mechanisms behind the improvement in Hci indicated that Ga ...