Electrochemical Behavior of Evaporated Copper/Gold Alloys

The preferential oxidation of copper from alloys was studied recently by Parks et al. 1 They found that the critical oxidation potential for ordered alloys was about 250 mV more noble than for disordered ones. In contrast, Moffat et al. 2 reported on experiments in which no such difference could be detected. Assuming that this discrepancy may be due to the preparation techniques, we investigated alloys prepared by evaporation. They were characterized by x‐ray diffraction. These samples show the same behavior as those prepared by Parks et al. Their and our preparation technique have in common that no polishing step was applied prior to the use of the alloy as an electrode, while Moffat et al. polished their alloys after the heat‐treatment.