Abstract
The problem of improving the mechanical properties of cast aluminum alloys by means of a complex modification of their structure is discussed. Fluxes widely used in industry are mainly aimed at modifying only one structural component of Al-Si alloys, which does not allow to unify the modification process in production conditions. Therefore, a new modifying flux has been developed that has a complex effect on the structure of silumins. It consists of: TiO2-a component containing an α-solid solution modifier; BaF2-a component containing a modifier of eutectic silicon; KF-a component that promotes the transition of titanium and barium to the melt. The effect of a complex modifier based on titanium dioxide on the macro-, microstructure and mechanical properties of cast aluminum-silicon alloys is studied for aluminum-silicon alloys: AK12, Ak9h, Ak7h, AK5M, AK18. It was found that the ultimate strength (σb) of silumins higher then similar characteristics for alloys modified with standard sodium-containing flux up to 32%, and the relative elongation (δ) increases to 54 %. It is shown that the increase in the mechanical properties of alloys is a consequence of the complex effect of the flux components on the macro-and microstructure, which consists in simultaneous grain grinding, grinding and more uniform distribution of the release of an α-solid solution of silicon in aluminum due to titanium, grinding and refining of silicon in eutectic using barium and potassium, and grinding of primary silicon. The authenticity of the research is confirmed by the use of modern test equipments, a significant amount of experimental data, and the repeatability of the results on a large number of samples in an identical initial state.
Keywords
Aluminum casting alloys, silumins, complex modification, titanium, barium, titanium dioxide, mechanical properties, microstructure, macrostructure, melt.