EMBRITTLEMENT OF NANO-SCALE STRUCTURES

A dealloyed surface layer formed on a Cu-30 Au alloy due to a corrosion process is capable of inducing intergranular cleavage of the normally ductile substrate during subsequent mechanical loading. The structure of the dealloyed layer consists of nanoscale pores that were formed by the selective removal of copper atoms during the anodic polarization. To contribute to the understanding of enviromentally-induced embrittlement, we presently compute the stress state within the porous layer and in the bulk substrate due to the eigenstraining by the dealloying. The results of the calculations show that a tensile stress state exists in the porous dealloyed layer while a compressive stress state is generated in the substrate. Implications on the "film-induced cleavage" model of stress corrosion cracking mechanism are discussed.