Influence of electromagnetic stirring and grain refinement on solidification defects in Al6Si2.5Cu alloy via X-ray computed tomography

This study investigates the combined effects of electromagnetic stirring (EMS) and chemical grain refinement (CGR) on solidification discontinuities in an Al-6wt%Si-2.5wt%Cu (Al6Si2.5Cu) alloy using 3D X-ray Computed Tomography. Results show that integrating EMS with an Al-5Ti-1B master alloy reduces the average grain size by 23.4% compared with CGR alone. This microstructural refinement produces a pronounced 57.95% reduction in total discontinuity volume and exhibits a near-cubic power-law dependence on grain size, with an exponent of 3.25. While the low-sphericity morphology characteristic of shrinkage cavities remains unchanged, the synergistic CGR + EMS treatment restricts the maximum defect size to below 0.4 mm, yielding a smaller, more homogeneously distributed defect population optimized for high-quality engineering components.