In this project metallic alloys, specifically designed for AM, with improved properties will be designed and produced by gas atomization in order to evaluate their processability in powder-based AM technologies. The project partners aim to develop new aluminum alloys (PoliTo, Leonardo and PoliMi), new titanium alloys (PoliTo and UniBg) and new Inconel alloys (PoliTo and UniNa) for use in advanced industrial applications.
New Al-based materials with tailored mechanical and functional properties (e.g. low Coefficient of Thermal Expansion, CTE, and improved ductility) will be design and produced according to the requests of the industrial partners. Indeed, Al alloys with proper thermal expansion behavior would be extremely important for all those applications in which dimensional stability is a key factor. The gas-atomization process will be optimized, and the obtained powders will be used to assess their processability by AM and to produce samples to characterize material features, including physical, microstructural and mechanical properties. The powders will be then used to print a medium-size mirror demonstrator, that will be tested. The alternative mirror substrate material with show favorable properties such as high stiffness and CTE compatible with that of the standard nickel plating.
Additive manufacturing processes will be applied to titanium alloys for harsh environments – e.g. palladium or ruthenium containing titanium alloys suitable for operating in reducing acid solutions – where they are considered as light-weight materials alternative to nickel superalloys. Different powder production techniques shall be considered covering either in-situ alloying or pre-alloying techniques (mechanical milling, gas atomization). Critical issues will be defined in relation to the operating conditions, to establish criteria of qualification according to more recent international guidelines. Effects of process parameters, post processing heat treatments and surface finishing on material properties will be studied, as well as corrosion resistance assessment. The qualification of additive manufactured materials for specific environments in advanced engineering application will be achieved.
Inconel alloys (most likely 718 and 725 grades) will be studied with the aim of developing AM processing routes with reduced environmental impact; in particular, three different aspects will be investigated: i) the process parameters for the printing process, with the aim of finding a methodology to reduce energy consumption during printing; ii) the study of the processing of the moulded parts sometimes necessary to reduce the surface roughness of the artefacts; a careful study of the processing will be carried out to reduce the environmental impact of this phase.
Finally, independently on the alloys, a special focus will be given to sustainability throughout their life cycle. In fact, the possibility of recycle and/or reuse process scraps and waste as feedstock to be used in gas atomization will be explored with the aim of dramatically improve the sustainability of the process.