Laser melting is a promising method for creating coatings with unique properties. In this paper, the microstructure of a coating made of quasicrystalline Al91Fe4Cr3Ti2 alloy obtained using this method is investigated. The coating is formed as a result of rapid solidification of the melt, which leads to the formation of a fine-grained structure enriched with quasicrystalline phases.
Microstructure analysis showed the presence of α-Al dendrites surrounded by a eutectic consisting of Al and a quasi-crystalline phase. The size of the dendrites and the morphology of the eutectic depend on the laser processing parameters. Increasing the laser scanning speed leads to a decrease in the size of the dendrites and a more uniform distribution of the quasi-crystalline phase.
Differential scanning calorimetry (DSC) was used to analyze a bulk sample of Al–Fe–Cr–Ti alloy, which has a composition favorable for the formation of quasicrystals. The sample was laser remelted to create a quasicrystalline surface layer.
After laser processing, the structure and properties of the material were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The data obtained indicate the possibility of forming porous coatings with inclusions of quasi-crystalline phases by laser remelting of a massive aluminum alloy.
In addition, microcracks are observed in the coating, which arise due to thermal stresses during rapid cooling. However, their number and size can be minimized by optimizing the laser processing parameters and alloy composition. The obtained results allow optimizing the laser melting process to create coatings with improved properties.
Author: P.Gargarella, A. Almeida, R. Vilar, CRM Afonso, CT Rios, C. Bolfarini, WJ Botta, CS Kiminami
Institute: Postgraduate Program in Materials Science and Engineering, Federal University of São Carlos, Washington-Louis Highway, km 235, 13565-905 São Carlos, São Paulo, Brazil, Department of Materials Science, IST-UTL, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal, National Synchrotron Radiation Laboratory (LME/LNLS), R. Giuseppe Maximo Scolaro, 10000 CP 6192, 13083-970 Campinas, São Paulo, Brazil, Department of Materials Science, Federal University of São Carlos, Washington-Luis Highway, km 235, 13565-905 São Carlos, São Paulo, Brazil