Alloys of the Al–Cu–Fe system containing a quasicrystalline phase are of considerable interest due to their unique physical and mechanical properties. However, for the widespread use of these materials, a detailed study of their corrosion resistance in various aggressive environments is necessary.
Studies show that the corrosion behavior of Al–Cu–Fe alloys is closely related to the alloy composition and microstructure, in particular, the presence and distribution of the quasicrystalline phase. The formation of a passive film on the alloy surface plays a key role in providing corrosion protection. Elements included in the alloy, such as aluminum, copper and iron, have different effects on the passivation process and the film’s resistance to localized destruction.
The influence of various factors, such as pH of the environment, temperature and the presence of chloride ions, on the corrosion resistance of Al–Cu–Fe alloys is also an important aspect of research. Understanding the corrosion mechanisms and factors influencing this process is necessary for developing effective methods of protection and improving the performance characteristics of these materials.
The corrosion behavior of quasicrystalline and crystalline phases in Al–Cu–Fe alloys, namely AlCu27.5Fe12.5, Al62.5Cu25Fe12.5, Al65Cu20Fe15 and Al67.5Cu20Fe12.5, was studied in different solutions. The corrosion resistance was evaluated by potentiodynamic polarization, and the microstructure was investigated by X-ray diffraction and scanning electron microscopy. The results showed that the composition and amount of phases in Al–Cu–Fe alloys are critical for the corrosion resistance.
In salt solutions, corrosion potentials resulted in uniform dissolution of the alloy followed by copper precipitation, with the corrosion rate depending on the amount of copper-rich phases. In acidic solutions, copper-rich phases remained stable, while phases with lower copper content were subject to corrosion. In neutral and alkaline solutions, the main reaction was surface oxidation, but Cu formed pores in the oxide layer, and Fe prevented oxidation. The quasi-crystalline phase with variable Cu and Fe content showed better corrosion resistance in neutral and alkaline environments.
Author: Elina Huttunen-Saarivirta, Tuomo Tiainen
Institute: Institute of Materials Science, Tampere University of Technology, P.O. Box 589, FIN-33101 Tampere, Finland