Search

High temperature corrosion of nanocrystalline MACu-20Ag-20Cr(at.%) alloy prepared by mechanical alloying(MA) was studied as compared with that of coarse grained PMCu-20Ag-20Cr alloy prepared by powder metallurgy(PM). PMCu-20Ag-20Cr alloy forms an external layer composed of CuO or CuO and CuCr 2 O 4 , while the internal layer is composed of alloys as well as Cu, Ag and Cr oxides. MACu-20Ag-20Cr alloy forms the same scale structures as PMCu-20Ag-20Cr alloy at 600 °C. On the contrary, it forms a bright layer of Ag 2 O at 700 °C, but an irregular and continuous layer of chromia at 800 °C, which prevent the alloy from being oxidized further. [ABSTRACT FROM AUTHOR]

Highlights: [•] Coarse-grained Cu–20Co–30Cr alloy is unable to form the scales of chromia. [•] Fine-grained Cu–20Co–30Cr alloy is able to form the scales of chromia. [•] The corrosion rates decrease significantly when the grain size is refined. [•] The grain refinement is benefit to form the scales of chromia in the alloy. [ABSTRACT FROM AUTHOR]