Effects of Solution Treated Temperature on the Structural and Magnetic Properties of Iron-Rich ${\rm Sm}({\rm CoFeCuZr})_{\rm Z}$ Sintered Magnet

The effects of solution-treatment temperature on the phase constitution, microstructure and magnetic properties of Sm(Co_bal.Fe_0.35Cu_0.06Zr_0.018)_7.8 were investigated systematically. The formation of Sm₂Co₇ around the Sm₂O₃ was confirmed and the volume fraction of Sm₂Co₇ increases with decreasing solution-treatment temperature. An area without cellular structure was observed around the Sm₂Co₇ phase in aged specimens solution treated at 1403 K. Thus, it was found that precipitation of Sm₂Co₇ phase prevents the formation of cellular structure during aging treatment. The coercivity of those magnets was less than 600 kA/m. On the other hand, the obvious formation of cellular structure was confirmed in the case of solution treatment at 1423 K and these magnets showed high coercivity of more than 1000 kA/m. The magnetic properties of M_r = 1.22 T and H_cJ = 1011 kA/m have been obtained for Sm(Co_bal.Fe_0.35Cu_0.06Zr_0.018)7.8 by solution treatment at 1423 K.