Effects of surface-active elements on wettability and interfacial reaction between DD5 superalloy and Al2O3-based ceramic shell

The study investigates the effects of oxygen-sulfur content, holding temperature, and time on the wettability and interfacial reactions between DD5 superalloy and Al 2 O 3 -based ceramic shells through non-in-situ sessile drop experiments. Lowering the oxygen-sulfur content in the DD5 master alloy, as well as reducing the holding temperature and time, leads to an increase in the wetting angle and a mitigation of interfacial reactions. Improved wettability promotes interfacial reactions, while intensified interfacial reactions further spread the alloy melt, enhancing its wettability. The main products of the interfacial reaction between the DD5 alloy and Al 2 O 3 -based ceramic shells are Al 2 O 3 and Si, with the process being influenced by the presence of Al. When the oxygen-sulfur content is controlled within 6 ppmw, the wettability will undergo a characteristic transformation, resulting in a sharp increase in the wetting angle. It demonstrates that the ultra-pure DD5 master alloy plays a crucial role in reducing wettability and interfacial reaction, as well as slowing down the tendency of the hetero-crystal formation. Therefore, it is of great engineering significance to further reduce the content of oxygen-sulfur impurity elements in DD5 superalloy. • The wetting angle decreases with the increase of the surface-active elements content. • The wettability will undergo a characteristic transformation within 6 ppmw. • The interfacial layer thickness increases with the increase of oxygen-sulfur content. • The ultra-pure DD5 master alloy also inhibits the tendency to form hetero-crystals.