M₂₃B₆金属硼化物是很多金属材料中的强化相。为揭示该化合物相在Fe-Co-B合金中的形成问题，本工作采用熔融玻璃净化法进行了名义成分合金(Fe_{1 - x} Co _x)_79.3B_20.7 (x = 0~1)的深过冷凝固实验。研究发现：当x ≤0.6时，随着过冷度的增加，初生相依次从M₂B、M₂₃B₆转变为α-M/M₃B，并且0.4 < x ≤0.6成分的合金存在L + M₂B→M₃B的包晶转变；对于x >0.6的合金，小过冷度下凝固的初生相为M₃B，随着过冷度的增加，初生相进一步从M₂B、M₂₃B₆向α-M/M₃B变化。随着Co含量增加，M₂₃B₆相析出的临界过冷度减小，M₂₃B₆相的稳定性提高。

M-B (M = Fe, Co, Ni) alloys have garnered significant attention in the automotive, petrochemical, and power electronics industries owing to their excellent corrosion resistance, wear resistance, and high-temperature strength. The service performances of the M-B alloys are closely related to that of borides. Among them, M₂₃B₆ generally exists as a metastable phase. However, the understanding of its formation is limited compared to that of other borides. To reveal the effect of Fe/Co content ratio on the solidification behavior of the Fe-Co-B alloys, particularly the formation of M₂₃B₆ phase, alloys with nominal composition of (Fe_{1 - x} Co _x)_79.3B_20.7 (x = 0-1) were undercooled using the melt fluxing technique. Consequently, the solidification behaviors were systematically investigated. With the increase in the Co content, the stable eutectic reaction changed from L→α-M + M₂B for x <0.4 to L→α-M + M₃B for x >0.4. Consequently, the two eutectic reactions occurred at the same temperature at x =0.4, and a peritectic reaction L + M₂B→M₃B was observed at x > 0.4. With the increase in the undercooling, the primary phase changes from M₂B and M₂₃B₆ to α-M/M₃B in the alloys with x ≤0.6, and from M₃B, M₂B, and M₂₃B₆ to α-M/M₃B in the alloys with x >0.6. The increase in Co content reduced the critical undercooling for the M₂₃B₆ phase to precipitate primarily and improved its stability, that is, the primary M₂₃B₆ phase decomposed into α-M/M₂B in the following cooling process when the Co content is not excessively high. However, it could sometimes be reserved to room temperature in case of a very large Co content.