Effect of Sb Addition on the Mechanical and Structural Behaviour of Sn-Bi alloy

Abstract

Sn-12wt.% Bi (alloy A) and Sn-12wt.% Bi-1wt.%Sb (alloy B) solder alloys homogenized at 463K for 24h were annealed for 2h at 443K. From both alloys a group of samples was slowly cooled to room temperature with a cooling rate of 1.2x10-2 K/s. A second group of samples was rapidly quenched in cold water (273K). Stress-strain, σ−ε, tests performed in the temperature range from (333-413) K in steps of 10 K, showed a temperature dependence of the hardening behaviour with minimum at 353K followed by a peak at 363K above which showed continuous decrease. The softening behaviour increased to 353K then showed minimum at 363K followed by continuous increase at higher temperatures for both alloys. In the low temperature range the softening coefficient, α, increased with Sb addition and its values were higher for the slowly cooled samples than the quenched samples. The intrinsic hardness at 0K, H o, was higher for the tertiary and quenched samples all over the tested temperature range. In the high temperature range, α showed a constant value of .02, Ho showed different values at 0K due to the different initial states of the tested samples. Increasing the temperature and Sb addition lead to more softening. The activation energy for the annealed and quenched samples of both alloys were found to be 16.72 and 19.144 kJ/mol for the low and high temperature regions, respectively.