Plastic Deformation Kinetics of Eutectic Pb-Sn Solder Joints in Monotonic Loading and Low-Cycle Fatigue

The deformation kinetics of near-eutectic Pb-Sn alloys in monotonic and cyclic loading in shear at 300K were investigated by determining the stress exponent n in the Dorn equation using several techniques including strain rate cycling. n was found to be a single-value function of the true stress for the present range of test conditions for both the monotonic and cyclic loading. It ranged from ~4 at the lowest stresses to ~30 at the highest stresses. The n-value of ~4 is concluded to represent dislocation glide and climb as the controlling mechanism, while values of n > 10 reflect power low breakdown.