Isotropic ${\hbox {Sm}}_{x}({\hbox {Co}},{\hbox {Fe}},{\hbox {Mn}})_{100mathchar$ Magnets via High-Energy Ball Milling

The combined Fe and Mn substitution for Co in intensively milled and annealed Sm-Co alloys was investigated for 9 at.% to 16.7 at.% Sm. A particular attention has been paid to the phase transformation occurring in the as-milled alloys at 450-800degC. In the Sm₂CO₁₇ alloy, the (Fe, Mn) substitution was superior to the Fe only substitution, as it markedly increased all the hard magnetic characteristics. In the Sm-lean alloys, the hard and soft magnetic phases showed poor exchange coupling. The (Fe, Mn)-substituted alloys did not outperform the Sm-rich Fe-substituted alloys, but showed better structure stability at the higher annealing temperatures. In particular, the Smu (Co, Fe, Mn)₈₉ alloy exhibited a maximum energy product of 15-16 MGOe when annealed at 700-750degC.