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Examined FeAl deposits were produced by low-pressure cold spray technique using heated air (300 °C, 15 bar) as working gas. Although metal powders were mixed in ratio 60/40 at% Fe/Al, the final chemical composition of the 8-10 mm thick deposits changed strongly favouring aluminium (approximately 80 at% Al). Samples consisting of the deposited material were annealed isothermally in argon protective atmosphere. All annealing processes ran at temperatures from 250 °C to 750 °C for two hours. The overall change of material character during annealing was evaluated: changes in the character of fracture behaviour, local micro hardness of the evolving phases and residual powder particles. Microstructure and chemistry of the newly formed phases was evaluated using analytical electron microscopy. First occurrence of intermetallic phases was observed at 550 °C. The evolved phases incurred by diffusion mechanism and included non-equilibrium and stable phases close to Al3Fe, FeAl, Al5Fe2 and Al2Fe. The general shape of the samples annealed at temperatures exceeding aluminium melting temperature was preserved due to a rapid formation of intermetallic skeleton. The growth of external dimensions and associated porosity evolution occurred during the treatment. In this paper, overall feasibility of the application of the presented technique for technically applicable materials and the aforementioned growth of external dimensions with porosity evolution are discussed.
Keywords: Cold spray, reaction synthesis, intermetallics, diffusion, metallic foam© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.