The influence of strain rate and temperature on plastic deformation behaviour of 63Sn/37Pb and 60Sn/40Pb solder alloys is investigated by means of a computer controlled servo-hydraulic machine over a temperature range of -40 to 80°C at constant strain rates of 10-3, 10-2 and 10-1 s-1. The fracture characteristics of deformed specimens are analyzed using scanning electron microscopy and correlated with macroscopic behaviour. The results indicate that the flow stress of both alloys is largely dependent on strain rate and temperature. The 63Sn/37Pb alloy, however, is stronger than 60Sn/40Pb over the range of 25 to 300°C. The change in flow behaviour is related to differential strain rates and temperature sensitivities. Over the strain rate and temperature range studied, 60Sn/40Pb exhibits higher strain rate and temperature sensitivities than 63Sn/37Pb. 60Sn/40Pb rupture resistance is found superior to 63Sn/37Pb in light of fracture observations revealing an absence of damage as well as an absence of flow instability. 63Sn/37Pb fracture is catastrophic at a strain rate of 10-3 s-1 and is characterized by shear. With decreasing test temperature, more edge cracks appear due to enhanced brittleness. The use of a deformation constitutive equation in combination with the parameter values obtained through these tests allows for an accurate description of the deformation behaviour of both tin-lead alloys over the range of conditions used in this study.
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