Author: D. J. Sordele, M. J. Kramer, O. Unal
Institute: Ames Laboratory, US Department of Energy, Iowa State University, 50011 Ames, Iowa, USA
The study of the influence of initial powders on the process of formation of the microstructure of quasicrystalline Al-Cu-Fe coatings by plasma spraying is relevant and significant in our time. Quasicrystals are a new generation of materials with unique properties such as high strength, wear resistance and corrosion resistance. However, effective control of the process of formation of the microstructure of quasicrystalline coatings remains a difficult task.
Powders and plasma-sprayed coatings of the Al63Cu25Fe12 alloy containing a quasicrystalline phase were characterized by X-ray diffraction, electron microscopy and differential thermal analysis. The relationships between powder and coating microstructures were investigated. Powders were obtained by casting and crushing, as well as gas atomization. Both technologies produced powders with multiple phases; cubic and monoclinic ternary structures were formed along with a face-centered icosahedral quasicrystalline phase. These phases have also been produced in plasma arc sprayed coatings formed using different starting powders. Cooling rates during powder processing strongly influenced the phase equilibria and extent of segregation of this alloy. The finer grain sizes in plasma sprayed coatings were obtained from more chemically homogeneous gas atomized powders.
The results of the study showed that the composition of the initial powders has a significant impact on the formation of the microstructure of quasicrystalline coatings. In particular, high aluminum and copper contents in powders lead to the formation of quasicrystalline phases with a larger grain structure, which ultimately leads to deterioration of the mechanical properties of coatings. On the other hand, the increased iron content in the initial powders contributes to the formation of a more compact and uniform microstructure of quasicrystalline coatings, which has a positive effect on their mechanical properties.
Thus, optimization of the composition of the initial powders is an important factor for controlling the formation of the microstructure of quasicrystalline Al-Cu-Fe coatings obtained by plasma spraying. Further research in this area may lead to the development of new methods and technologies that will achieve higher productivity and improved mechanical properties of quasicrystalline coatings.