Masaya Hagiwara

Effects of Solution Treated Temperature on the Structural and Magnetic Properties of Iron-Rich

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.

{\rm Sm}({\rm CoFeCuZr})_{\rm Z}

In this study, we investigated intermediate-heat treatment (IHT) at temperatures between those of sintering and solution treatment, and evaluated the effects on the macrostructure, microstructure, and magnetic properties of Sm(Cobal.Fe0.35Cu0.06Zr0.018)7.8. We found that squareness was clearly improved by adopting the IHT, which promotes grain growth. These results indicate that reducing the fraction of grain boundaries by increasing the grain size affects the behavior of domain-wall motion. Magnetic properties of Mr 1.22 T, HcJ 1580 kA/m, and (BH)max 282 kJ/m3 (>35 MGOe) were obtained for Sm(Cobal.Fe0.35Cu0.06Zr0.018)7.8 subjected to IHT at 1453 K.