合金的形核机制及其控制方法是凝固理论的重要研究领域之一。 触发形核方式可自主控制形核过冷度，对 研究形核理论及组织演变具有极大帮助。 但熔体具有亚稳性，在实际处理时，外源性杂质引入熔体后将作为触发形核异质点，改变过冷度 ΔT 和再辉度 ΔTR，显著影响后续凝固行为，该种现象更为普遍。 本文通过玻璃包覆结合循环过热过冷方式， 获得两类不同形核模式凝固的 Co80B20 合金。 自发形核模式下，ΔT 及 ΔTR 分别为 280 和 199 K， 组织组成为Co/Co3B 细小规则共晶。 外源性触发形核模式下，ΔT 和 ΔTR 降至 122 和 21 K。 组织转变为初生 Co 枝晶及晶间的 Co23B6基体相。 外源性杂质将降低 f(θ)，减小临界形核半径，降低 ΔT，使得组织更加不均匀，在实际的熔体处理过程中应予以控制。

The nucleation mechanism of alloys and control methods are important research areas for solidification theory. The triggered nucleation method can autonomously control the undercooling degree of nucleation, which is highly useful for studying nucleation theory and microstructure evolution. However, the melt is metastable. In the actual treatment, the introduction of exogenous impurities into the melt will be used as a heteroamorous point for triggered nucleation, changing the undercooling degree ΔT and remelting degree ΔTR, and further significantly affecting the subsequent solidification behavior, which is more common. In this paper, two types of Co80B20 alloys solidified via different nucleation modes were obtained by glass coating combined with cyclic superheating and undercooling. In the spontaneous nucleation mode, ΔT and ΔTR are 280 and 199 K, respectively, and the microstructure is composed of a fine, regular eutectic Co/Co3B. In the exogenously triggered nucleation mode, ΔT and ΔTR decrease to 122 and 21 K, respectively. The microstructure is transformed into primary Co dendrites and intergranular Co23B6 matrix phases. Exogenous impurities reduce f(θ), the critical nucleation radius and ΔT, increasing the inhomogeneity of the structure, which should be controlled during actual melt treatment.