Influence of phase transformation on the work hardening characteristics of Pb-(1-3)wt.%Sb alloys

Abstract

This study focuses on the effect of phase transformation on the work hardening characteristics of Pb-(1-3)wt.%Sb alloys either quenched (type I) or slowly cooled samples (type II) at different ageing temperature (Ta). Three work hardening characteristics were studied which are; the coefficient of work hardening p, yield stress σy and fracture stress σf. It was found that; these parameters of both types of samples decrease with increasing Ta, showing two stages around the transformation temperature which changes with the Sb addition and equal to 453 K for 1wt.%Sb, 483 K for 2wt.%Sb and 513 K for 3wt.%Sb. The values of these parameters of type I samples were higher than type II samples. The fracture strain εf, the strain at the fracture point, increases with increasing Ta showing two stages also. The dislocation slip distance, L, increases as Ta increases. The magnitude of the variation of all these parameters point to two fracture mechanisms activated with 0.11 and 0.39 eV for 1wt.%Sb, 0.15 and 0.49 eV for 2wt.%Sb, 0.20 and 0.65 eV for 3wt.%Sb for type I samples and equal 0.21 and 0.52 eV for 1wt.%Sb, 0.17 and 0.56 eV for 2wt.%Sb, 0.16 and 0.63 eV for 3wt.%Sb for type II for both first and second stages, respectively. The microstructure of the samples under investigation has been examined after stress-strain measurements by scanning electron microscope.