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An ultrasonic vibration-assisted air-cooled stirring rod process (ACSR + UV) was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg.A low-cost Al-Si-Fe-Mg-Cu-Zn die-casted alloy with high thermal conductivity,high plasticity and medium strength was developed.The alloy was used to manufacture large,thin-walled parts for 5G base stations by using the ACSR + UV rheological die-casting (ACSR + UV R-DC) process.Investigations were performed on the microstructure,porosity,mechanical properties,fracture behaviour and thermal conductivity of the ACSR + UV R-DC alloy,which was then compared to traditionally die-casted (T-DC) and ACSR R-DC alloys.The mecha-nisms for the microstructural refinement and enhancement of the mechanical and thermal conductivity performances of the ACSR + UV R-DC alloy were also analysed.The results showed that the ACSR + UV process increased the nucleation rate of the melt due to the increase in the nucleation area and the generation of cavitation bubbles.A radial-and an axial-forced convection was also generated inside the melt under the combined effects of acoustic flow and mechanical stirring,thereby homogenising the melt composition field and the temperature field.Therefore,the ACSR + UV R-DC process not only refined the primary α-Al (α1-Al),the eutectic silicon and the secondary α-Al (α2-Al),but also greatly improved the mor-phology and the distribution of the β-Al5FeSi phase.The mechanical properties of the ACSR + UV R-DC alloy were higher than those of the T-DC and the ACSR R-DC alloys.Compared to the T-DC alloy,the ultimate tensile strength,elongation and yield strength of the ACSR + UV R-DC alloy were increased by 34％,122％ and 19％,respectively.This was because the ACSR + UV R-DC technique gave the alloy the characteristics of high density,fine spherical α1-Al grain and a fine and uniform β-phase,which improved the fracture behaviour of the alloy.The thermal conductivity of the ACSR + UV R-DC alloy was 184 W/(m K),which was 10.2％ and 3.4％ higher than that of T-DC and ACSR R-DC alloys,respectively.This was because the refined eutectic silicon and β phases in the ACSR + UV R-DC alloy facilitated an easier electron flow through the eutectic region,and the decrease in porosity increased the effective area of heat conduction.