Abstract
The electrochemical behaviors of the Ni-base superalloy CMSX-4 were carried out in 3.5 wt.% NaCl solution using electrochemical technique. The electrochemical corrosion process was divided into four stages, and reactions at the alloy surface and corrosion morphology at each stage were analyzed. The passivity mechanism at the stable passivation stage and the occurrence of pitting corrosion at the transpassivation state were discussed especially. The corrosion parameters including Ecorr, Epass, ipass and Epit were compared at different temperatures to reveal the relationship between the temperature and the corrosion resistance properties. The corrosion products were investigated by the aid of X-Ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). By designing different preoxidation procedures, the corrosion mechanism of oxide scales was analyzed for the preoxidized samples.
Highlights
Ni-base superalloys have the ability to resist a wide variety of corrosive environments and loads over extended periods of time, becoming unique high-temperature materials used in turbine blades of industrial processes [1,2,3,4]
The oxidation behavior of the single-crystal PWA 1438 at 950 ◦ C in flowing air is characterized by the formation of a multi-layered oxide scale [8]
The ingots of the alloys were prepared by vacuum induction melting (VIM) and the compositions were measured by inductively-coupled plasma-optical emission spectroscopy (ICP-OES) at NCS
Summary
Ni-base superalloys have the ability to resist a wide variety of corrosive environments and loads over extended periods of time, becoming unique high-temperature materials used in turbine blades of industrial processes [1,2,3,4]. The CMSX-4 superalloy is a versatile alloy which has excellent corrosion resistance characteristics, and is widely applied in the fields of aircraft, marine engineering, and some military equipment [5,6,7]. In order to prolong the using life of the CMSX-4 superalloy, considerations should be given to its corrosion behaviors, together with their strong dependence on temperature and preoxidation procedures. Oxidation of Co-base superalloys at high temperatures in air happens in two stages: a transient period and a subsequent steady-state period in which several oxides
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