Processing and thermomechanical properties of immiscible AlSi5-Sn alloys produced by plasma wire arc additive manufacturing

Plasma Wire Arc Additive Manufacturing (PWAAM) rises up as cost-effective technique to produce quasi-net shape parts. The introduction of independent feeding devices makes it suitable to produce materials with adjustable composition. The present paper illustrates the alloy design, processing optimization and thermophysical characterization of PWAAM applied to combined Sn and AlSi5 alloy, separately fed, which behave as immiscible systems. This aims to explore the suitability of the resulting welds for Thermal Energy Storage/Thermal Management as well as for bearings purposes. PWAAM was employed for the production of Al5Si + 20%vol.Sn (40 wt%) and functionally graded welds, with different Sn content, deposited on Al substrates. The resulting microstructure qualitatively met the target requirements, showing preliminary stability even after ten simulated service heat cycles. As far as the thermal and the mechanical responses are concerned, Differential Scanning Calorimetry (DSC), dilatometry, Laser Flash Analysis (LFA), microhardness and compression tests show comparable results with the literature-gathered ones, testifying the effectiveness of the technology. However, the presence of local Sn accumulations and the possible development of cracks related to the process still claim process optimization.