## 3 Results and Discussion
### Microstructure Analysis  
To confirm the suitability of the homogenization conditions at 580 \({}^{\circ}\)C and 600 \({}^{\circ}\)C, as predicted by the DSC measurement, the as-cast samples were exposed to 580 \({}^{\circ}\)C and 600 \({}^{\circ}\)C for 4, 5, 6, 7, 8, 9, 10, 11 and 12 h. All samples were examined under a light microscope, of which only the microstructures of the samples tested at 580 \({}^{\circ}\)C and 600 \({}^{\circ}\)C for 6 and 10 h are shown in Figure 2. At 500\(\times\) magnification, sample K0 shows noticeable differences in its intermetallic phase shapes and sizes, with fine spherical and rod-shaped particles likely representing metastable iron-based phases. A darker, more distinct phase, possibly the stable Al\({}_{13}\)Fe\({}_{4}\) phase, is also observed, as noted in references [29; 30]. As the homogenization time increases, the growth of the stable Al\({}_{13}\)Fe\({}_{4}\) phase in this region becomes evident, while the particles of the phase in the eutectic region grow. After 6 h of homogenization at 580 \({}^{\circ}\)C (K0-580 \({}^{\circ}\)C/6 h), the proportion of fine spherical particles of the metastable phase decreases significantly but is still visible. In the sample that was homogenized for 10 h, the metastable Al\({}_{6}\)Fe phase is no longer visible, as it has completely transformed into a stable Al\({}_{13}\)Fe\({}_{4}\) phase. This phase also appears in a more agglomerated form. When adding Ce and/or La, the continuous network of eutectic structure Al-Fe phase broke down and to more dispersed and divorced morphology, consistent with [21]. As reported in [29], Ce and La are incorporated into the Al-Fe eutectic, which cannot be seen in the optical micrographs, but the eutectic phases in as-cast state formed by Ce and La are (\(\alpha\)-Al + Al\({}_{11}\)Ce\({}_{3}\)) and (\(\alpha\)-Al + Al\({}_{11}\)La\({}_{3}\)). These phases are unevenly distributed in the alloy. In all cases, K1, K2, and K3, the completion of the homogenization process cannot be predicted from these micrographs after 6 h but can be predicted after 10 h of homogenization. A similar finding was also made for homogenization at 600 \({}^{\circ}\)C (Figure 3), although the proportion of homogenized Fe phases after 6 h is higher than that at a homogenization temperature of 580 \({}^{\circ}\)C (Figure 2). It can be said that homogenization is mostly finished after 6 h and is  
Figure 1: DSC measurement of homogenization annealing simulations of Al-1.4 wt.% Fe alloys at 580 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, and 620 \({}^{\circ}\)C.  
completed after 10 h at 600 \({}^{\circ}\)C. The degree of homogenization cannot be specified for the Ce- and La-bearing phases, as they cannot be distinguished in the microstructure.  
To be sure that Ce- and La-containing phases were also formed and homogenized, SEM images and EDS maps were made of all the alloys studied, which were homogenized  
Figure 3: Optical micrographs of the as-cast samples and homogenized samples at 600 \({}^{\circ}\)C for 6 h and 10 h at magnification 500.  
Figure 2: Optical micrographs of the as-cast samples and homogenized samples at 580 \({}^{\circ}\)C for 6 h and 10 h at magnification 500.  
at a temperature of 580 \({}^{\circ}\)C for 10 h (Figures 4-7). These images confirm the assumptions of the previous analysis regarding the Fe-containing phases, which appear in the matrix in a spherical form and lower density. The Al\({}_{13}\)Fe\({}_{4}\) phase is thermodynamically more stable than the metastable particles in these conditions. As was reported in [21,22] the presence of Ce in Al-1.4 wt.% Fe alloy can presumably result in the formation of Al\({}_{10}\)Fe\({}_{2}\)Ce compounds. This was also the case in our study, which is shown in Figures 6 and 7, where Ce and Fe appear simultaneously in the mapping. The Ce- and La-containing eutectic phases also agglomerate, with La phases (Figures 5 and 7) forming more spherical shapes, while Ce phases (Figures 6 and 7) typically appear as rods and claws.