Achieving further refinement of grain structure and improvement of mechanical properties in Al-12Si-4Cu-2Ni-1Mg alloy by Al-Ti-C-B master alloy addition and deep cryogenic treatment

• Combining Al-Ti-C-B master alloy addition with deep cryogenic treatment (DCT) reduces average grain size of Al-12Si-4Cu-2Ni-1Mg alloy from 0.92 mm to 0.50 mm, achieving significant grain refinement. • DCT for 24 hours followed by aging spheroidizes and refines eutectic Si and Al7Cu4Ni precipitates, enhancing microstructural uniformity. • The refined microstructure leads to a 22.5% increase in elongation and a 6.8% improvement in tensile strength, while also significantly extending fatigue life. • This novel strategy offers an environmentally friendly and effective method to overcome Si poisoning in grain refinement of near-eutectic Al-Si alloys, with potential for automotive lightweighting applications.