Stress Corrosion Cracking of Cu-9 at%Al Alloy Bicrystals

Abstract

The effect of grain boundary on stress corrosion cracking (SCC) was studied on Cu-9 at%Al alloy bicrystal specimens with <111>-tilt Σ=13b coincidence boundary in (NH₄OH+NaOH) solution at 303±2K. It was found that SCC occurred in all specimens having the stress ratio (σ_a/σ_y) between 0.92 and 1.25, where σ_a and σ_y are the applied and yield stresses, respectively. Susceptibility to SCC was found to be much greater at the grain boundary compared to the crystal surface, and all specimens fractured intergranually. Time for the initiation of SCC at grain boundary was found to depend on the applied stress ratio. Prestraining made the alloy more susceptible to SCC at grain boundary and accelerated the crack initiation at grain boundary. No influence of prestraining on SCC at crystal surface was observed.