Accelerating the design of highly separable Fe-containing intermetallics in Al–Si alloys via DFT calculations and experimental validation

The detrimental Fe element in Al-Si cast alloy can be effectively removed by Fe-containing intermetallics separation. However, the formation temperature of Fe-containing intermetallics can be further improved to increase the removal efficiency of Fe element. The effects of the Cr/Mn atomic ratio on the stability, theoretical melting point, elastic modulus, and thermal properties were calculated with the aim of improving the stability of the α-Al(FeMnCr)Si phase. An increased Cr/Mn atomic ratio effectively increased the stability, theoretical melting point, elastic modulus, isobaric heat capacity, and reduced the volumetric thermal expansion coefficient of α-Al(FeMnCr)Si phase, which can be explained by the strengthened Al-Cr and Si-Cr chemical bonds. The experimental study results revealed that the formation temperature and Young's modulus of the α-Al(FeMnCr)Si phase increase from 673.0°C and 228.5 GPa to 732.0°C and 272.1 GPa with the Cr/Mn atomic ratio increasing from 0.11 to 0.8, which better validates the thermodynamic stability, theoretical melting point and elastic modulus calculation results. These results provide a new strategy for designing Fe-containing intermetallics with the desired properties, which contributes to guiding the development of high-performance recycled Al-Si alloys.