Effect of Ag + ion concentration on the stress corrosion cracking susceptibility of Ag–Cd alloys in AgNO 3 and AgClO 4 aqueous solutions

Abstract

Silver–cadmium alloys, with compositions ranging from Ag–10Cd (a/o) up to Ag–40Cd (a/o) were found to be susceptible to stress corrosion cracking (SCC) in silver nitrate and in silver perchlorate aqueous solutions, at the equilibrium potential of the reaction: Ag⇌Ag ++e −. The effect of Ag + ion concentration on the stress corrosion cracking propagation rate (CPR) was studied. A linear relation between the logarithm of the CPR and the logarithm of the Ag + concentration was found. The slope of this relation was very close to that reported for the silver exchange current density and the silver ion concentration: (δ log i 0/δ log [ Ag +]) . Most of the cracks found were transgranular, and the crack propagation mechanism was explained through the surface mobility SCC mechanism. In the present work, it is suggested that Ag–Cd alloys could be used as model alloys to study the SCC behaviour of technically more relevant alloys, such as Cu–Zn brasses.