Anodic dissolution of iron and cobalt germanides in an alkaline electrolyte

Anodic dissolution of iron and cobalt germanides and their eutectic alloys with germanium in 1 M NaOH was studied by electrochemical methods and microprobe analysis. In anodically etching the FeGe2−Ge and CoGe2−Ge eutectic alloys, it was the Ge phase that predominantly dissolved in the alkaline solution, while the FeGe2 intermetallic phase was found to be more stable than both Ge and a pure iron germanide. The anodic dissolution of FeGe2 revealed a passive range (which is absent in acidic solutions) attributed to the oxidation of iron, probably, to γ-Fe2O3.