Thermal cycling of Pb/Sn eutectic alloy

Severe deformation, annealed and thermal cycling are employed on Pb/Sn eutectic alloy. The cycling was carried out between room temperature and 140 C, and the cycling number ranged from 0 to 1300 cycles. Microstructural studies revealed that grain size and volume fraction were increased by thermal cycling. The morphology of lamellar structure changed to spherical structure by severe deformation and annealing. No effect of thermal cycling on morphology was observed. The dimensional change after cycling was anisotropic; the length expanded, whereas the width and thickness shrank. These changes in dimensions are attributed to elastic and plastic strains, and / or creep strain. Preliminary tensile test measurements showed that ''m''-value decreased by cycling. Also, total ductility decreased. These are due to the increase in both grain size and volume fraction. (orig.)