High temperature corrosion behavior of Cu–20Co–30Cr alloys with different grain size

•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.

The corrosion behavior of Cu–20Co–30Cr alloys with different grain size was investigated at 700–900 °C in 0.1 MPa pure oxygen. The corrosion rates of fine-grained MACu–20Co–30Cr alloy are significantly lower than those of coarse-grained PMCu–20Co–30Cr alloy. PMCu–20Co–30Cr alloy forms the external scales of Cu oxides followed by an internal oxidation region containing alloy and a mixture of Cu, Co and Cr oxides as well as their complex oxides. MACu–20Co–30Cr alloy forms the continuous scales of chromia and a Cr-depleted layer occurs beneath the scales. The grain refinement is helpful to form the continuous scales of chromia in a Cu–Co–Cr alloy.

Graphical abstractThe grain refinement is benefit to form the scales of chromia in Cu–20Co–30Cr alloy.Figure optionsDownload full-size imageDownload as PowerPoint slide