Microstructural and performance evolution of solidified aluminum under permanent magnet stirring

• Using permanent magnet stirring technique to improve the pure Al grain structure. • The effect of RMF on pure Al grain refinement largely relies on their purity level. • Hardness and electrical conductivity are highly correlated with pure Al grain size. • Discussing the grain refinement mechanism of pure Al by permanent magnet stirring. The technological progress of permanent magnet stirring (PMS) is of great significance for solidified aluminum grain refinement. A comparative study has been carried out to explore the microstructural and performance evolution of solidified aluminum with three purity grades under various rotating magnetic field (RMF) schemes induced by PMS. The experimental results suggest that the use of RMFs can produce fine and homogeneous equiaxed grain structures of solidified aluminum, and the influence of RMFs on grain refinement strongly depends on the purity level of solidified aluminum. The tendency changes of hardness and electrical conductivity are highly correlated with that of grain size. Moreover, the reasons have also been discussed to explain the effect of PMS on the microstructural evolution of solidified aluminum.