Effect of Fe Content on Phase Behavior of Sm–Co–Fe Alloys During Solidification and Aging

The effect of different Fe contents on the phases of Sm-Co-Fe ternary alloys during solidification is investigated herein by melting the alloys using a non-consumable vacuum arc furnace. In particular, the phases of the Sm_25.5Co_balFe_x (<i>x</i> = 19, 21, 23, and 25 wt.%) alloys are investigated after solidification and aging. The results obtained from Cai Li's modified Miedema model show a strong interaction between the Sm-Co alloy atoms. Additionally, the results obtained from the Toop geometric model show a strong interaction between the Sm-Co-Fe ternary alloy atoms, enabling the formation of intermetallic compounds. The experimental results show that when the Sm content is 25.5 wt.%, the SmCo₅ phase gradually decreases as the Fe content increases and disappears when the Fe content is 25 wt.%. Thermodynamic calculations show that when the Fe content is 19 wt.%, there is a region where the SmCo₅ and Sm₂Co₁₇ phases co-exist. As the Fe content increases, this region gradually decreases. For a 25 wt.% Fe content, the Sm₂Co₁₇ and SmCo₅ two-phase region does not appear when the Sm content varies. The samples are aged at 1143 °C for 12 h, then melted and cut. The phase results obtained by scanning are consistent with the calculated results. In this study, the effect of each constituent element of Sm-Co-Fe ternary alloys on their solidification phases is investigated, providing a strong foundation for studying the 2:17-type Sm-Co magnetic materials obtained after melting and aging a five-element Sm-Co alloy.