本文通过比较在四种实验条件下Cu-80wt%Pb过偏晶合金的凝固组织，研究了实验参数对过偏晶合金组织结构的影响。重点分析了在Pb基体内富Cu相的结构和形成机制，以及冷却速度和强磁场的影响作用。实验结果表明了球形富Cu相主要有三种结构，即“网壳型”、“卵型”、“眼型”。冷却速度对其宏观和微观组织有较大的影响。通过对比，发现随着冷却速度的降低，Pb基体中的富Cu相由细小的球相转变为上浮聚集的粗大球相，直至只有Cu枝晶留在富Pb基体中。冷却速度的降低使得富Cu球相Cu壳的厚度增加，其内部的网状结构粗化；施加12T强磁场能够抑制富Cu液滴的上浮和富Pb相的沉积，对Cu-Pb合金的重力偏析产生一定的抑制作用，所得到的偏晶合金宏观和微观结构与无磁场时冷速较快的结构相类似。对于较大的富Cu液滴，强磁场具有抑制球相内外Cu溶质迁移的作用，抑制了球壳的增厚和网状组织的粗化。
The solidification process of Cu-80wt%Pb hypermonotectic alloys was investigated in four different experiment conditions. The formation process and structure of Cu-rich sphere phase has been analyzed, and the influence of high magnetic field and cooling rate have been considered. The results show that the morphology of spherical Cu-rich phases mainly has three kinds of microstructure, that is the larger “net-shell type” and the smaller “egg-type” or “eye-type”. The cooling rate of the samples has great effect on both macrostructure and microstructure. As the cooling rate become slow, the Cu-rich phase changed from the fine sphere to the larger floating sphere and the finally coarse dendrite, and the thickness of Cu-shell and reticulum of Cu-Pb in Cu-rich sphere phase became coarser; The 12T high magnetic fields have a remarkably effect of restraining the gravity segregation of Cu-Pb alloy by preventing from the floating of larger Cu-rich droplets and sedimentation of Pb-matrix, so that a macrostructure and microstructure of Cu-Pb monotectic alloy similar to one under relative fast cooling rate is formed. And the 12T high magnetic field maybe has the effect to inhibit the transition of Cu solute both outside and inside of Cu-rich sphere phase, which inhibit the Cu-rich shell from becoming thicker, and the Cu-Pb “net-like” phase from coarsening.
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