Achieving superplastic properties in a Pb–Sn eutectic alloy processed by equal-channel angular pressing

摘要

Experiments were conducted on a Pb-62% Sn eutectic alloy containing 160 ppm of Sb. The alloy was processed by equal-channel angular pressing (ECAP) through 1 to 5 passes at room temperature and then tested in tension at a temperature of 423 K using initial strain rates from 1.0 × 10−4 to 1.0 × 10−1 s−1. Excellent superplastic elongations were achieved at intermediate strain rates with a maximum elongation to failure of 2,665%. It is shown that, for processing through similar numbers of ECAP passes, these elongations are higher than in an earlier investigation using a Pb-62% Sn alloy of higher purity. The results are presented pictorially in the form of a deformation mechanism map by plotting normalized grain size against normalized stress at a temperature of 423 K.