Assessment of Directionally Solidified Eutectic Sm–Fe(Co)–Ti Alloys as Permanent Magnet Materials

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IEEE Transactions on Magnetics
Sm–Fe–Ti and Sm–Fe 0.8 Co 0.2 –Ti alloys were prepared via arc-melting and directionally solidified on a water-cooled copper hearth. The as-solidified alloys featured cells of the Sm(Fe,Co,Ti) 12 –Ti(Fe,Co) 2+δ –(α-Fe) lamellar eutectic. The lamellae of Sm(Fe,Co,Ti) 12 phase with a crystal structure of the ThMn12 type were less than 0.2 μm thick, and had their [001] easy-magnetization directions oriented along the temperature gradient of the solidification. The eutectic microstructure led to an increased coercivity, especially in the Co-added alloys. Below 250 °C, this coercivity was found not to vary much with temperature with a temperature coefficient of -0.18 %/°C. However, the modest absolute values, reaching only 0.7 kOe, are insufficient for utilization of the directionally solidified alloys as anisotropic permanent magnets.
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magnetic materials, metallurgy, permanent magnets, samarium compounds, ThMn12 type
A. M. Gabay, C. Han, C. Ni and G. C. Hadjipanayis, "Assessment of Directionally Solidified Eutectic Sm–Fe(Co)–Ti Alloys as Permanent Magnet Materials," in IEEE Transactions on Magnetics, doi: 10.1109/TMAG.2023.3280849.