The oxidation behaviour of homogeneous Ni \(_{29}\) Fe \(_{56}\) Cu \(_{15}\) wt.%, Ni \(_{42}\) Fe \(_{38}\) Cu \(_{20}\) wt.% and Ni \(_{60}\) Fe \(_{30}\) Cu \(_{10}\) wt.% is investigated under 1 atm flux of high-purity O \(_2\) gas—using thermogravimetry—with respect to application as oxygen-evolving anodes for aluminium electrolysis. Stable cubic oxidation behaviour was observed in Ni \(_{42}\) Fe \(_{38}\) Cu \(_{20}\) wt.% and Ni \(_{60}\) Fe \(_{30}\) Cu \(_{10}\) wt.% after 30 h and 264 h, respectively, with the former showing particular promise for electrowinning applications due to a tendency to form a well-adhered scale consisting of approximately 70% NiFe \(_2\) O \(_4\) by thickness, as measured from EDX line scans. NiO dominated the scale of Ni \(_{60}\) Fe \(_{30}\) Cu \(_{10}\) wt.% up to 272 h, showing worse scale adhesion and prominent intergranular oxidation of iron. Partially blistered regions of the scale locally increased NiO/CuO formation in Ni \(_{42}\) Fe \(_{38}\) Cu \(_{20}\) wt.%, evolved to become (Cu/Ni, Fe)O spinel oxides over time.
