## 3 Results and Discussion of the Research Results
Therefore, the addition of silicon in the master alloy has a beneficial effect on the refinement of the eutectic alloy. Similar observations were made for the mechanical properties. Rm = 169 MPa (Figure 3f), A = 4% (Figure 4f) and H = 60 HB (Figure 5f) were obtained, which is an increase in strength by 12% and elongation by 81% compared to the alloy after modification with titanium but without silicon. After modifying the silumin master alloy (0.06% B + 7% Si + Al), a microstructure was obtained, consisting of large-sized plates with parallel axes of symmetry within the boundaries of individual grains (Figure 2g), but with slightly coarser grains than after the modification with (0.06% Ti + 7% Si + Al) (Figure 2f), and finer than after modification with (0.06% B + Al). Similar relationships were observed for the mechanical properties, Rm = 163 MPa (Figure 3d), A = 3.2% (Figure 4d) and H = 58 HB (Figure 5d). These observations confirm once again that the master alloy containing silicon (therefore a component of the modified alloy) has a more intense effect than the master alloy without silicon. Test results were also obtained, indicating a higher effectiveness of the impact on microstructure refinement and increase in the mechanical properties of titanium than boron. The greatest refinement of the AlSi7 Mg alloy microstructure (both the eutectic and the primary \(\alpha\) phase) was observed after the modification of the master alloy composed of (0.06% Ti + 0.06% B + 7% Si) (Figure 2h). The microstructure after modification with this modifier still consists of lamellar eutectic (\(\alpha\) + \(\beta\)) against the background of the \(\alpha\) phase, but with a large dispersion of the \(\beta\) phase and fine dendrites of the \(\alpha\) phase. This microstructure is reflected in the highest mechanical properties in the analyzed test plan; Rm = 181 MPa (Figure 3d), A = 5.1% (Figure 4d), H = 61 HB (Figure 5d). The effectiveness of introducing modifier components into the AlSi7 Mg alloy was confirmed via an XRD analysis. An example record for the master alloy modification (0.06% Ti + 0.06% B + 7% Si + Al) is shown in Figure 6. On this basis, the presence of titanium and boron introduced into the alloy via the master alloy was confirmed. The introduction of aluminum and silicon cannot be confirmed because these chemical elements are a natural component of the tested alloy (they occur naturally in silumin). It should be noted that the amount of individual chemical elements introduced in the form of the master alloy in relation to the mass of the processed alloy is small. This is the reason for small peaks confirming individual phases. However, the purpose of the XRD analysis was not to determine the content of individual elements in the alloy, but only to confirm their transition from the master alloy to silumin. Analyzing the obtained results of the mechanical properties tests (Figures 3-5), it was found that both titanium and boron influence the increase in the analyzed parameters. Both of these components, both together and separately, have a more intense effect when silicon is included in the master alloy. The modification of the silumin master alloy (Si + Al) did not bring any significant benefits. When comparing the effectiveness of titanium and boron, small differences were found. In the absence of silicon in the master alloy (lower level of the research plan), boron has a more effective impact on the refinement of the microstructure and the increase in mechanical properties. However, when the silicon content in the master alloy is similar to the silicon content in the modified alloy, titanium is more effective. With the above in mind, it was decided to conduct further research using, in addition to titanium and boron, a solid component in the master alloy in the form of (Al + 7% Si). It was shown [67] that hypoeutectic Al-Si casting alloys are most effectively fragmented via small additions of boron above 0.01% by weight.