Film-induced brittle intergranular cracking of silver-gold alloys

Dealloying of a binary noble alloy produces a porous layer rich in the more noble element. Application of a tensile load initiates a brittle intergranular (IG) crack in the dealloyed layer that advances into the unattacked material. This study showed that the crack penetration depth (C-d) is proportional to the thickness of the dealloyed layer (t). For a given value oft, the grain-boundary crack penetration distance was shown to decrease as the dealloying potential increased. The dependence of C-d On t and the dealloying potential, as opposed to the applied potential at the time of fracture, supported the film-induced cleavage model.