Grain refinement mechanism of Al–Sc alloys by electromagnetic directional solidification with high Sc composition design

Al–Sc alloys are emerging lightweight structural materials critical for defense and electronics, yet suffer from severe Sc segregation and grain coarsening in conventional processes. This study introduces electromagnetic directional solidification with coupled physical fields to regulate solidification. A systematic investigation of the grain refinement mechanisms of Al 3 Sc primary phases and their multi-scale structural evolution revealed that the Al-20at.%Sc alloy demonstrated significant refinement under optimized electromagnetic parameters (i.e., a high induction current and low solidification velocity). This resulted in the formation of a gradient structure with Al 3 Sc as the core, encapsulated α-Al phase, and an outer layer of eutectic Al 3 Sc. A metallurgical transport model established via multi-physics coupling simulations demonstrated that electromagnetic stirring suppressed macroscopic Sc segregation and enhanced melt convection, thereby promoting the heterogeneous nucleation density. This research provides theoretical guidance for the industrial production of highly homogeneous Al–Sc alloys. • A new method for the preparation of Al–Sc alloys by electromagnetically directional solidification. • Various high-purity Al–Sc alloys with differing Sc contents were studied. • Fine and uniform grains in Al–Sc alloys achieved with high current and low pulling speeds. • Particle growth model developed from Al 3 Sc morphology under different conditions. • Grain refinement mechanism of Al–Sc alloys clarified by solidification simulation.