Creep of Pb–2·5Sb–0·2Sn alloy at low stresses

Abstract

AbstractThe creep of a Pb–2·5Sb–0·2Sn alloy has been studied at stresses up to 6·5 MN m−2 in the temperature range 318–348 K (0·53–0·58Tm) using helical specimens. At 333 K, a transition in the stress exponent from ~1 to 3 occurred at ~3 MN m−2. The observed good agreements below the transition stress, both for experimental dE/do and predictions for Coble diffusional creep of lead, and for measured activation energy for creep and the activation energy for grain boundary self-diffusion in lead, suggest that grain boundary diffusional creep is the dominant mechanism. at low stresses. The presence of antimony does not seem to affect the magnitude of dE/do appreciably, and the results suggest that the grain boundary self-diffusivity of lead is not influenced by the presence of segregated antimony on the grain boundaries. The diffusional creep occurred above a threshold stress of magnitude ~0·5 MN m−2, and its temperature dependence was characterised by an activation energy of ~20 kJ mol−1, similar to the valu...