Surface Properties of Liquid Al-Si Alloys

The present work is aimed to highlight the interfacial properties (surface tension and wettability) of metallic systems involved in the additive manufacturing processing (AM) and their importance for design and development of new candidate materials as it has been already done in the field of joining processes (soldering, brazing, welding). The surface properties of Al-12.6Si (in wt pct) alloy, taken as a reference alloy of a class of additive manufacturing Al-Si based alloys, were investigated. The contact angles of pure Al and of Al-12.6Si alloy in contact with Al2O3 substrates were obtained by applying the sessile drop method under different working atmospheres. The new reference data on the wetting properties of the Al-12.6Si/Al2O3 system can be useful for design and development of new Al-Si-based alloys to be used in AM. The surface tension and the surface segregation of liquid Al-Si alloys were calculated as functions of composition by using Butler's model and the results obtained were compared to available literature data.