A Cr2O3-deposited Sm(Co0.68Fe0.22Cu0.08Zr0.02)7.5 magnet with increased oxidation resistance at 700 °C

Abstract A Sm(Co 0.68 Fe 0.22 Cu 0.08 Zr 0.02 ) 7.5 alloy was arc-ion-plated with a thin Cr 2 O 3 film. It completely prevented the external oxidation and sufficiently suppressed the internal oxidation of the alloy in air at 700 °C for 20 h, causing the alloy to form only a very shallow layer where the Sm oxidation occurred. The mechanism for the effect of the Cr 2 O 3 film on the oxidation of the alloy was proposed based on phase characterization of the oxidized layer.