## 4 Results and Discussion
### Compositional Sensitivity
The addition of components such as Al\({}_{2}\)O\({}_{3}\), CaO, and MgO lead to significant contractions in the miscibility gap limiting the compositional range of stability where liquid immiscibility is favored. This is in agreement with [14], whose work indicated a suppression of the miscibility gap with the addition of these components. The contraction of the phase boundary with additions of \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**LFe-Dispersed**} & \multicolumn{2}{c}{**LSi-Dispersed**} \\ \hline Component & SEM & TEM & SEM & TEM \\ SiO\({}_{2}\) & 50.2 \(\pm\) 3.1 & 44.6 \(\pm\) 8.9 & 32.5 \(\pm\) 1.6 & 25.2 \(\pm\) 0.8 \\ FeO & 41.4 \(\pm\) 4.0 & 45.2 \(\pm\) 6.3 & 61.0 \(\pm\) 3.1 & 67.1 \(\pm\) 6.0 \\ Al\({}_{2}\)O\({}_{3}\) & 5.9 \(\pm\) 0.5 & 6.8 \(\pm\) 1.4 & 4.6 \(\pm\) 0.3 & 4.8 \(\pm\) 0.1 \\ CaO & 1.0 \(\pm\) 0.1 & 1.3 \(\pm\) 0.2 & 0.6 \(\pm\) 0.1 & 1.8 \(\pm\) 0.02 \\ MgO & 1.5 \(\pm\) 0.2 & 2.1 \(\pm\) 0.4 & 1.3 \(\pm\) 0.1 & 1.2 \(\pm\) 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Bulk composition of amoeboids as measured by SEM (average) and TEM in oxide weight percent. alkaline +2 oxides shifts the phase boundary towards SiO\({}_{2}\) (depletion in FeO) as reported by [40]. The bulk compositions for the L\({}_{\text{Fe}}\)-dispersed (red-dashed lines) and L\({}_{\text{Si}}\)-dispersed (green-dashed lines) amoeboids, as measured by SEM-EDS (left-dashed lines) and TEM-EDS (right-dashed lines) can be shown relative to these calculations. Superimposing the observed compositions with the model suggests that the L\({}_{\text{Si}}\)-dispersed amoeboid compositions would fail to experience stable phase separation with the combined addition of 5 wt% Al\({}_{2}\)O\({}_{3}\), 2% CaO, and 1% MgO. From the observed fallout microstructures, the L\({}_{\text{Fe}}\)-dispersed and L\({}_{\text{Si}}\)-dispersed amoeboid compositions are expected to lie on opposite sides of the miscibility gap compared to their dispersed phase. Where the dispersed phase is the minority phase, such that LSi-dispersed comprises an iron-rich matrix that includes Si-rich dispersed. However, CALPHAD predictions would expect both amoeboid morphologies to be L\({}_{\text{Si}}\).dispersed, where the majority phase is FeO-rich according to the lever rule [42], since both compositions lie on the iron-rich side of the miscibility gap. From Figure 2b, it can be seen that the experimentally observed compositions of the L\({}_{\text{Fe}}\)-dispersed amoeboids lie on the iron-rich side of the miscibility gap. However, the observed L\({}_{\text{Fe}}\)-dispersed morphologies indicate that the iron-rich dispersed phase should correspond to the minority phase, although phase fractions of the relative amounts of L\({}_{\text{Fe}}\) and L\({}_{\text{Si}}\) liquid phases were not measured experimentally. Conversely, the L\({}_{\text{Si}}\)-dispersed amoeboid morphology is expected to contain an FeO-rich majority phase and a dispersed L\({}_{\text{Si}}\)-rich minority phase; this is accurately represented in Figure 2b. Equilibrium calculations predict an L\({}_{\text{Fe}}\)-dispersed phase (where the majority phase is SiO\({}_{2}\) rich) at composition <30 wt% FeO, and the L\({}_{\text{Si}}\)-dispersed phase (majority phase FeO-rich amoeboids) at compositions >30 wt%. While these calculations demonstrate immiscibility sensitivity to overall composition, they do not consider alkali components such as Na\({}_{2}\)O or K\({}_{2}\)O. These metal oxide species undoubtedly play a role in constraining the miscibility region [40], but they are not represented in our equilibrium calculations due to constraints on the available elements in the TAF-ID database.