Pb-Sn eutectic alloys were deformed in compression at room temperature in the as-cast condition. The microstructural change during deformation and nonuniform deformation with boundary sliding were investigated in a metallographic point of view.
Boundary sliding occurred mainly at the interface between colonies in the initial deformation stage. Dynamically recrystallized grains were formed at the colony boundaries and developed into matrix with increasing strain. In the lamella structure region, lamella structures were destabilized and changed to equiaxed grains of Pb and Sn phases during deformation. In the massive structure region, equiaxed subgrains were formed by deformation in the large grains of Pb and Sn phases. These processes to make equiaxed structure are very important for as cast Pb-Sn eutectic to deform superplastically according to grain boundary sliding.