The development of efficient methods for the mass synthesis of quasicrystalline materials (QC) is a pressing issue in modern materials science. One promising approach is the spray treatment (STP) of alloys, which allows obtaining large volumes of QC powders with controlled characteristics.
This study is devoted to the investigation of the possibility of mass synthesis of the QC phase in Al–Cu–Fe and Al–Cu–Fe–Sn alloys by the RPO method. Varying the sputtering parameters, such as melt temperature, gas pressure and disk rotation speed, allows optimizing the process of QC phase formation.
In Al–Cu–Fe alloys, the formation of the icosahedral phase (i-phase) is observed in a wide range of compositions. The addition of tin (Sn) helps stabilize the i-phase and improve its morphology. The optimal Sn content ensures the formation of uniform QC particles with a minimum number of crystalline inclusions.
In this study, Al-Cu-Fe alloys with and without addition of Sn, as well as alloys containing a quasicrystalline phase, were prepared and characterized using the sputtering technique. The resulting sputtered materials were carefully analyzed for microstructural features and hardness characteristics. It was observed that the Al62.5Cu25Fe12.5 alloy is characterized by the presence of an icosahedral quasicrystalline phase (i-phase) and a minor λ-Al13Fe4 phase. Meanwhile, the Al62.5Cu25Fe12.5 alloy with the addition of Sn exhibits the presence of five phases: the dominant i-phase and the crystalline phases of Sn, θ-Al2Cu, λ-Al13Fe4, and β-AlFe(Cu). These results were confirmed using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and differential scanning calorimetry (DSC).
The hardness of the Al–Cu–Fe alloy reached 10.5 GPa at a load of 50 g, showing a subsequent decrease with increasing load. In the case of the Al–Cu–Fe–Sn alloy, the initial hardness was somewhat lower, with a sharp drop with a small increase in load, but then stabilized with further increases. When hard particles were pressed into the Al–Cu–Fe alloy, crack formation was observed, while in the Al–Cu–Fe–Sn alloy, areas with a higher tin content served as a barrier preventing crack propagation. This study provides a better understanding of the mechanisms of phase and microstructural changes occurring during the sputtering of the studied alloys. Particular attention is paid to the role of tin in the context of the microstructure and properties of the materials.
Microstructural analysis of powders obtained by the RPO method revealed the presence of a QC phase with particle sizes ranging from several micrometers to tens of micrometers. The studies conducted by the differential scanning calorimetry (DSC) method showed high thermal stability of the obtained QC materials.
In conclusion, the RPO method is an effective way of mass synthesis of Al–Cu–Fe and Al–Cu–Fe–Sn QC powders. Varying the alloy composition and spraying parameters allows controlling the phase composition, morphology and thermal stability of the obtained materials. The obtained QC powders can be used to create functional materials with unique properties.
Author: V. C. Srivastava, E. Huttunen-Saarivirta, C. Cui, V. Uhlenwinkel, A. Schulz, N. K. Mukhopadhyay
Institute: National Metallurgical Laboratory, Jamshedpur, 831007, India, Department of Materials Science, Tampere University of Technology, P.O. Box 589, Tampere, FI-33101, Finland, Institute for Materials Science, University of Bremen, Bad Gasteinerstrasse 3, 28359 Bremen, Germany, Department of Metallurgy, Indian Institute of Technology (BHU), Varanasi, 221005, India