High-temperature oxidation of Cu-30 wt.% Ni-15 wt.% Fe

The oxidation behaviour of Cu-30 wt.% Ni-15 wt.% Fe has been investigated from 750 degreesC to 1000 degreesC in 1 atm oxygen. The oxidation mechanism is complex and changes with temperature. Above 900 degreesC, the kinetics are approximately parabolic, and the oxidation involves an external growth of Cu oxides and an internal oxidation of Ni and Fe. The oxide scale consists of an outer Cu oxide layer and an inner multi-phase region. At 750 degreesC, Cu oxides, NiO and nickel ferrite are formed as layers in a repeating sequence. The layered oxide morphology is reflected in complex oxidation kinetics. The change in oxidation behaviour reflects the transition from an internal oxidation of Ni, at high temperatures, to an essentially continuous NiO barrier layer at lower temperatures. (C) 2001 Elsevier Science Ltd. All rights reserved.