## 3 Results and Discussion
or to a mismatch compared to Al\({}_{82}\)Fe\({}_{16}\)Ce\({}_{2}\). As [PERSON] et al. [46] reported, the GFA of the Al-Ni-RE alloy prepared by the rapid quenching technique exhibited a strong dependence on the size of the RE atom. As the atomic radius of the RE element increases, the GFA of the amorphous alloys also increases. Furthermore, we consider the amorphization of Al\({}_{82}\)Fe\({}_{16}\)Ce\({}_{2}\) and Al\({}_{82}\)Fe\({}_{16}\)Y\({}_{2}\)[39] alloys, which contain rare elements and were prepared by mechanical alloying using the same planetary ball mill. Interestingly, both alloys satisfy all three of [PERSON]'s criteria. Each alloy consists of three elements, with the mixing enthalpies for element pairs Al-Y and Al-Ce being \(-\)38 kJ/mole, and for Fe-Ce and Fe-Y being \(+\)3 and \(-\)1 kJ/mole, respectively. Therefore, both alloys exhibit nearly similar mixing enthalpies between atomic pairs. Al exhibits atomic size mismatches of 21.8% with Ce and 21.4% with Y, while Fe displays mismatches of 32.2% and 31.8% with Ce and Y, respectively. However, the Al\({}_{82}\)Fe\({}_{16}\)Ce\({}_{2}\) and Al\({}_{82}\)Fe\({}_{16}\)Y\({}_{2}\) alloys achieved a full amorphous structure after 40 and 100 h of milling, respectively. Both alloys have similar physical properties, including atomic radius (Y: 180 pm, Ce: 181 pm), boiling point (Y: 3345 \({}^{\circ}\)C, Ce: 3426 \({}^{\circ}\)C), and Pauling electronegativity (Y: 1.22, Ce: 1.12). The electrical structural perspectives offer a deeper comprehension of the stability of metallic glasses. There is a significant difference in the electron configurations of Ce and Y. Cerium, with its 58 electrons, exhibits a more complicated electron configuration compared to yttrium, which contains just 39 electrons. This increased complexity in Ce's electronic structure could enhance chemical disorder during the milling process, potentially contributing to a higher glass-forming ability (GFA) [48]. In addition, raw Ce powders have a particle size of 248 um (\(-\)60 mesh), which is smaller than that of Y powders of 372.5 um. The amorphization process is initiated by the MA, which deforms the powder particles through a series of cold welding and fragmentation cycles, ultimately resulting in a fully amorphous structure. The rapid size reduction process leads to a faster amorphous phase completion. In this context, Y has a bigger initial particle size than that of Ce, so it takes a longer time for the milling to produce amorphous alloys. Additionally, the inherent metallic ductility of Y tends to favor the cold-welding process, dominating over fragmentation during milling. This effect is clearly demonstrated in the detailed analysis presented in our previous article [39]. The reduction of particle size and cold-welding lead to the extension of the amorphization of Al-Fe-Y. On the contrary, because of the presence of Ce in the Al-Fe-Ce alloy, the fragmentation process dominates, so the particle size of the mixture powders decreases rapidly, causing the amorphization process to take place after only 40 h (Figure 3). As seen in SEM micrographs of the MAed Al\({}_{82}\)Fe\({}_{16}\)Ce\({}_{2}\) powders (Figure 3) milled at different times, most particles are flattened due to the collision between powders,