Improvement of anti-oxidation capability and tribological property of arc ion plated Ag film by alloying with Cu

► Ag-Cu alloy film was deposited by arc ion plating (AIP) and show considerable resistance to atomic oxygen (AO) irradiation. ► The affected thickness of Ag-Cu alloy film by atomic oxygen was greatly reduced and the oxidation product was mainly Ag2O, but AgO and Ag2O in case of pure Ag film. ► As a result, the Ag-Cu alloy film exhibited a stable friction and low wear after the AO irradiation compared with pure Ag film.