부산대학교 도서관

Magnetic properties of directly quenched ${\hbox{R}}_{9.5}{\hbox{Fe}}_{72.5\hbox{-}{\rm y}}{\hbox{Ti}}_{2.5}{\hbox{Zr}}_{0.5}{\hbox{Cr}}_{\rm y}{\hbox{B}}_{15 \hbox{-}{\rm x}}{\hbox{C}}_{\rm x}$ (${\hbox{R}}={\hbox{Nd}}$, Pr, and mischmetals (MM); ${\rm x}=0\hbox{-}0.5$; ${\rm y}=0\hbox{-}1$) bulk magnets with a diameter of 0.9-1.1 mm and a length of 15 mm have been studied. Thermal magnetic analyses show that large amount of 2:14:1 phase together with a slight $\alpha\hbox{-}{\hbox{Fe}}$ phase are found for most of the developed magnets. Besides, a slight substitution of C for B and Cr for Fe in ${\hbox{Nd}}_{9.5}{\hbox{Fe}}_{72.5}{\hbox{Ti}}_{2.5}{\hbox{Zr}}_{0.5}{\hbox{B}}_{15}$ magnets can effectively refine the grain size of the bulk magnet, resulting in the remarkable enhancement of the magnetic properties. The optimal magnetic properties of ${\hbox{Br}} = 5.9~{\hbox{kG}}$, ${}_{\rm i}{\hbox{H}}_{\rm c}=8.2~\hbox{kOe}$ and $({\hbox{BH}})_{\max}=7.2~\hbox{MGOe}$ could be attained in ${\hbox{Nd}}_{9.5}{\hbox{Fe}}_{71.5}{\hbox{Ti}}_{2.5}{\hbox{Zr}}_{0.5}{\hbox{Cr}}_1{\hbox{B}}_{14.5}{\hbox{C}}_{0.5}$ . In addition, for ${\hbox{R}}_{9.5}{\hbox{Fe}}_{71.5}{\hbox{Ti}}_{2.5}{\hbox{Zr}}_{0.5}{\hbox{Cr}}_1{\hbox{B}}_{14.5}{\hbox{C}}_{0.5}$ magnets, even though the magnets with ${\hbox{R}}={\hbox{MM}}$ exhibit slightly lower ${\hbox{B}}_{\rm r}$ and $({\hbox{BH}})_{\max}$ than the magnet with ${\hbox{R}}={\hbox{Nd}}$ , magnetic properties of ${\hbox{B}}_{\rm r}=5.6\hbox{-}5.7~{\hbox{kG}}$, ${}_{\rm i}{\hbox{H}}_{\rm c}=10.3 \hbox{-}11.4~{\hbox{kOe}}$ , and $({\hbox{BH}})_{\max}=6.0\hbox{-}6.9~{\hbox{MGOe}}$ can also be achieved for the magnets with ${\hbox{R}} = {\rm MM(A)}$ and MM(B).