Aluminum-quasicrystal composites are promising alloys for additive manufacturing, but their evaluation can be costly. Recently, it was demonstrated that laser deposition can form the desired composite microstructure in Al85Cu6Fe3Cr6 alloy over a wide range of laser processing parameters.
In this paper, the thermal stability of microstructures obtained by laser deposition is assessed. The studies were carried out using scanning transmission electron microscopy in situ on samples prepared by ion-beam processing in the center of the tracks. The initial microstructure was a uniform distribution of 70% quasicrystalline inclusions of the I-phase in the FCC aluminum matrix, with a thin layer of Al2Cu at the interface.
Preliminary experiments on step heating allowed us to determine the temperatures of phase transformations, after which isothermal experiments were carried out on new samples to study these processes in detail. At temperatures up to 450 °C, only redistribution and an increase in the particle size of the Al2Cu phase, as well as a gradual increase in the iron concentration in this phase, were observed. At higher temperatures, the I-phase decomposed to form a mixture of ω-Al7Cu2Fe and μ-Al4Cr crystalline phases. The decomposition of the I-phase was accompanied by the release of Cu and Fe, and areas with a high Cr content were transformed into the approximating Al4Cr phase. The consequences of the observed phenomena for the application of this alloy in additive manufacturing technologies are discussed.
In this paper, we investigate the microstructural changes occurring in the Al-Cu-Fe-Cr alloy reinforced with quasicrystalline particles after laser treatment. We study the influence of laser exposure parameters on the formation and evolution of the microstructure in the heat-affected zone and the fusion zone. It is established that laser treatment leads to a redistribution of the alloy components, a change in the morphology of quasicrystalline particles, and the formation of new phases.
Quasicrystalline Al-Cu-Fe-Cr alloys have unique properties such as high hardness, wear resistance and corrosion resistance. Reinforcement of metal matrices with these alloys allows creating composite materials with improved performance characteristics. Laser processing is a promising method of modifying the surface of materials, allowing local changes in their microstructure and properties.
The material used for the study was an Al-Cu-Fe-Cr alloy reinforced with quasi-crystalline particles. Laser processing was performed using a YAG laser with different power and scanning speed parameters. Microstructural studies were carried out using optical and electron microscopy, as well as X-ray diffraction.
It has been established that laser processing leads to significant changes in the alloy microstructure. In the heat-affected zone, matrix grain growth and changes in the morphology of quasicrystalline particles are observed. In the fusion zone, the material is remelted and new phases are formed, such as Al-Cu and Al-Fe intermetallics. The laser processing parameters have a significant effect on the size and morphology of the fusion zone, as well as on the distribution of alloy components.
Laser processing is an effective method for modifying the microstructure of the Al-Cu-Fe-Cr alloy reinforced with a quasicrystal. By varying the parameters of laser action, it is possible to control the size and morphology of the fusion zone, as well as the phase composition of the material. The results obtained can be used to create new composite materials with improved properties.
Author: J. Saelzera, G. Polus a, A. L. Meijer, T. Wolf, J. F. Gerken a, J. Baumann, A. Zabel, D. Biermann, M. Sipura, N. Piljic
Institute: Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136, USA, Department of Physics, University of Connecticut, Storrs, CT 06269-3046, USA