Synergistic enhancement of Al-Si7Mg alloy: Strengthening mechanical properties through combined electromagnetic agitation and AL-10%Ti refinement

Abstract

Al-Si7Mg alloy is widely used in automotive and aerospace applications due to its favorable strength-to-weight ratio and corrosion resistance. However, further enhancement of its mechanical properties remains a key challenge. While grain refinement through chemical additives is common, the synergistic effect of combining a chemical grain refiner with external electromagnetic agitation during solidification has not been fully explored. This study investigates the simultaneous application of Al-10%Ti grain refiner and electromagnetic agitation, via a custom electromagnetic force (EMF) coil, on the microstructure and mechanical properties of Al-Si7Mg alloy. The EMF voltage was varied from 0 to 220 V. Microstructural analysis revealed that the combined treatment effectively transformed coarse, acicular silicon phases into a fine, closed-grain structure. This refinement is attributed to the electromagnetic agitation promoting uniform dispersion and increased potency of Al-10%Ti particles, which act as heterogeneous nucleation sites. The optimized microstructure led to significant improvements in mechanical properties: the sample treated with Al-10%Ti and 180 V EMF exhibited a maximum ultimate tensile strength of 173.3 N/ mm2, representing a 15% increase over the untreated baseline. Hardness improved by 21%, elongation increased by 60%, and wear resistance was notably enhanced, particularly at higher EMF levels (180–220 V). The results demonstrate that the combined approach offers a synergistic mechanism for microstructural refinement and property enhancement in Al-Si7Mg alloy, providing a promising route for advanced casting processes.