**4. Conclusions**

The developed complex flux consists of available substances that are widely produced by the industry and has a significant effect on the mechanical properties and structure of hypoeutectic, eutectic, hypereutectic aluminium–silicon alloys.


**Author Contributions:** Supervision, A.P.R.; writing—original draft preparation, A.D.S. and I.A.P.; writing—review and editing, A.D.S., I.A.P. and V.V.T.; investigations, A.D.S., I.A.P., E.V.M. and A.P.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research was carried out within the state assignment (No. FUER-2019-0004).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
