Al–Cu–Fe quasicrystals are a special class of materials with unique physical and chemical properties due to their aperiodic atomic structure. The production of quasicrystalline alloys by melt spinning is an effective way to achieve a high degree of structural order and homogeneity.
In this paper, the conditions for obtaining a quasicrystalline phase in the Al–Cu–Fe system by melt spinning were investigated. The process parameters, such as the roller rotation speed, melt temperature, and alloy composition, were varied in order to optimize the conditions for the formation of a quasicrystalline structure.
The resulting tapes were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns showed the presence of characteristic diffraction peaks corresponding to the icosahedral phase, confirming the formation of a quasi-crystalline structure. Microstructural analysis using SEM revealed a uniform distribution of elements and the absence of visible crystalline inclusions.
Three aluminum-copper-iron alloys with compositions in the range of Al60–65Cu20–27.5Fe12.5–15 were prepared using standard casting technology and then subjected to additional processing by spin casting. The resulting structures were analyzed to understand the correlation between the synthesis and processing methods, as well as the resulting microstructure of these Al–Cu–Fe alloys. The main objective of the study was to find out whether it is possible to create single-component quasi-crystalline bands using the spin casting method and how the level of supercooling affects the formation of the microstructure of the bands obtained by this method.
As a result of the peritectic reaction between the primary β-AlFe phase and the liquid solution, the icosahedral ψ-Al65Cu20Fe15 phase is formed with decreasing temperature. At later stages of cooling, the monoclinic λ-Al13Fe4 phase and the tetragonal θ-Al2Cu phase are formed in the cast alloys by peritectic reactions. In the alloys solidified at a high rate, the formation of the tetragonal θ-Al2Cu phase and, in the case of the Al60Cu25Fe15 alloy, the monoclinic λ-Al13Fe4 phase is not observed, which is probably due to the high degree of undercooling. Therefore, the production of single-phase quasi-crystalline tapes by spin casting seems impossible, at least when using a cooling rate in the range of 5–7×104 °C/s. In addition to the phase selection, the amount of supercooling affects characteristics such as the composition of the ψ-Al65Cu20Fe15 phase and the grain morphology in the spin-casting tapes.
The thermal stability of Al–Cu–Fe quasicrystals was studied using differential scanning calorimetry (DSC). The results showed high thermal stability of the quasicrystalline phase, which is an important factor for the practical application of the material.
Thus, the melt spinning method is an effective way to obtain Al–Cu–Fe quasicrystals with a high degree of structural order and thermal stability. The obtained materials can be used in various fields, including catalysis, thermoelectricity and protective coatings.
Author: Elina Huttunen-Saarivirta, Jyrki Vuorinen
Institute: Institute of Materials Science, Tampere University of Technology, P.O. Box 589, FI-33101 Tampere, Finland, Epanet, Southern Ostrobothnia University Network, P.O. Box 151, FI-60101 Seinäjoki, Finland