The Influence of Complex Modification on the Structure of Complex-Alloy Hypereutectic Silumin

Abstract—This work is devoted to the study of the influence of complex modification on the microstructure of complex-alloy hypereutectic silumin of the Al–Si–Cu–Mg–Ni–Mn system. The task of the work was to determine the phase composition of the alloy in the cast state. The analysis of literature and multicomponent phase diagrams was carried out. The phase composition was studied using scanning electron microscopy (SEM), energy-dispersive X-ray spectral microanalysis, and X-ray phase analysis (XRD) of the studied alloy. Various modifying elements and their modifying mechanisms are considered. For modification of complex-alloy hypereutectic silumin the following additives were used: K₂TiF₆ and K₂ZrF₆ salts, complex-modifying fluxes (CMFs), a tableted refining-modifying preparation (RMP), and a phosphorus-containing ligature. The effect of complex modification on the coefficient of thermal linear expansion (CTLE), hardness, and microhardness of primary silicon of complex-alloy hypereutectic silumin was assessed. Microstructural studies of the effect of complex modification on the sizes of primary and eutectic silicon were conducted. The studies showed that the use of complex modification is a relevant direction for improving the structure of complex-alloy hypereutectic silumins and increasing their properties.