分别以Co47.5Cu47.5Pb5和Co42.5Cu42.5Pb15三元偏晶合金作为母合金，采用单辊法急冷快速凝固制备Co-Cu-Pb三元难混溶合金颗粒，对颗粒的微观组织结构与尺寸进行观察与分析，并对不同结构颗粒的形成机制进行研究。结果表明：Co-Cu-Pb合金颗粒的直径为70~600μm，得到实心颗粒、空心颗粒及多层壳核结构3种不同结构的颗粒。Co-Cu-Pb合金颗粒发生包晶反应形成富Co(Cu)相的初生枝晶，富Pb相主要富集于枝晶间隙处。随辊面线速度从15 m/s增大到30 m/s，初生Co(Cu)相枝晶发生粗大枝晶→细小等轴晶的转变，合金颗粒的凝固组织显著细化，并且由于液态难混溶合金发生 Marangoni 运动，形成快速凝固多层壳核结构，最终获得均质化的 Co-Cu-Pb合金凝固组织。%Using Co47.5Cu47.5Pb5 and Co42.5Cu42.5Pb15 ternary monotectic alloys as master alloys, the Co-Cu-Pb ternary immiscible alloy particles were prepared by rapid solidification. The size and microstructure of alloy particles were analyzed, and the formation mechanism of particles with different structures was investigated. The results showd that the alloy particles with diameters in the range of 70−600μm had three kinds of structures, i.e. solid particle, hollow particle and core-shell particle. Under rapid solidification, the Co(Cu) phase in Co-Cu-Pb alloy particle grew into primary dendrite through the peritectic reaction and Pb phase mainly distributed in the interdendritic boundary. With the roller speeds increasing from 15 m/s to 30 m/s, the primary Co(Cu) phase dendrite transformed from coarse dendrite to fine equiaxed dendrite, and the microstructure of the alloy particles was remarkably refined. Meanwhile, through reducing the Pb content, the Marangoni convection of liquid metals in immiscible alloy occured. The core-shell structure with rapid solidified multilayer was formed and the homogeneous microstructure was finally obtained.
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