Influences of alloyed Si on the corrosion resistance of Co-Cr-Mo alloy to molten Al by iso-thermal oxidation in air

The corrosion resistance of Co-Cr-Mo alloys with various Si concentrations after oxidation to molten Al was investigated. Si was helpful in forming a more homogeneous, compact Cr2O3 film after oxidation. Correspondingly, the Cr2O3-dominant film was more effective in enhancing the corrosion resistance than the duplex film of CoO and Cr2O3 of alloy with low Si concentration. In addition, local defects such as the cracks acted as initiation sites of failure in oxide film. Ascribed to its higher stability, Si-rich layer beneath the oxide film delayed the reaction between Al and matrix even after the failure of oxide film. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.