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.

The grain refinement is benefit to form the scales of chromia in Cu–20Co–30Cr alloy.Figure optionsDownload as PowerPoint slide