On corrosion-induced stress states in binary noble metal alloys

The corrosion-induced stress state in dealloyed noble metal alloys is evaluated through the methods of continuum eigenstrain analysis. Microstresses are then determined employing the formalism of doublet mechanics. For partially dealloyed Cu-Au alloy plates, the stress state is tensile at the dealloyed surface decreasing to a maximum compressive stress in the interior of the layer, the magnitude of which increases with increasing overall Cu content in the starting alloy and decreases with increasing thickness of the dealloyed region. The undealloyed 'substrate' region immediately adjacent to the dealloyed layer is in a state of tension, the magnitude of which increases with overall starting Cu content and dealloyed region thickness. This stress state is interpreted to lead to defect segregation to the plate surface and to the dealloyed layer/substrate interface.