Electrodeposition and characterization of Au-Cu-Cd alloys

The electrodeposition of Au-Cu-Cd alloys from cyanide baths was investigated under different hydrodynamic conditions. Alloys obtained at different current densities were characterized from the compositional, structural and morphological points of view. Depending on the electrodeposition current density, the deposit structure displays either one or two-phase disordered solid solutions; corresponding changes in mechanical properties were observed. Morphology and roughness show a marked smoothing transition when the current density is increased over the limit for the inception of Cu codeposition. The Cd2+ concentration in the bath is a critical factor for control of the electrodeposition process, especially in respect to compositional stability and absence of hydrogen incorporation. Alloy composition was shown to be critically affected by hydrodynamic conditions; strict control of flow conditions is needed in order to obtain alloys of desired and reproducible composition.