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对Pb-30%Bi包晶合金进行定向凝固试验,研究了在不同生长速率、不同试样直径条件下获得的两相微观组织,并对其组织的形成及微观组织尺度进行分析。试验结果表明,当生长速率V由1μm/s逐渐增大到100μm/s时,微观组织经历胞状初生α相+胞间包晶β相到枝晶状α相+枝晶间β相微观组织的转变。当生长速率V≤0.5μm/s时,在小直径(1.8 mm)试样中发现不完全带状组织,而在大直径(7 mm)试样中却得到了振荡组织。同时发现,初生α相的一次枝晶间距λ与凝固速率V之间存在λV0.16=241.0μm1.16s-0.16的关系,这与Hunt模型和Trivedi模型较好地吻合。
Directional solidification experiments were carried out on Pb-30% Bi-peritectic alloys. Two-phase microstructures obtained under different growth rates and different sample diameters were studied. The formation and microstructure of Pb-30% Bi were also analyzed. The experimental results showed that the microstructure underwent the transformation from primary α phase + intergranular β phase to β phase of dendritic α phase + dendrite when the growth rate V was gradually increased from 1μm / s to 100μm / s change. When the growth rate V≤0.5μm / s, incomplete banding was found in the small diameter (1.8 mm) specimens, whereas in the large diameter (7 mm) specimens, the oscillating structure was obtained. At the same time, it is found that there exists λV0.16 = 241.0μm1.16s-0.16 between the primary dendritic spacing λ of the primary α phase and the solidification rate V, which is in good agreement with the Hunt model and the Trivedi model.