Synergistic regulation of microstructure and properties in 3003 aluminum alloy by La microalloying and pulsed magnetic field: From casting to ultra-thin foil

Conventional cast 3003 aluminum alloy develops coarse grains and network-like intermetallic phases. Its cold-rolled foils suffer pinhole defects and an inherent strength-conductivity trade-off, while routine homogenization annealing is energy-intensive and time-consuming. Herein, an integrated modification route combining La microalloying and low-energy pulsed magnetic field (LE-PMF) is proposed for 0.4 wt.% La-bearing 3003 alloy. The full microstructure evolution from as-cast ingot to 0.02 mm ultra-thin foil, together with mechanical and electrical performances, was systematically investigated to reveal the synergistic regulation mechanism and casting microstructure heredity upon heavy rolling. Results indicate that LE-PMF realizes prominent grain and precipitate refinement. The optimal grain refinement occurs at 50 mT, reducing average grain size from 121.0 μm to 107.0 μm (11% refinement rate). At 80 mT, coarse Al6(Mn, Fe) and AlLaSi network phases transform into fine spherical particles with an average diameter of 2.34 μm, superior to 600 ℃ homogenization. Optimized cast structure inherits well during heavy rolling and eliminates forming defects. Foils treated at 80 mT achieve tensile strength elevated from 225 MPa to 423 MPa, and the peak conductivity of 67.8 %IACS (13% improvement) is obtained at 110 mT. The La-LE-PMF coupling breaks the alloy strength-conductivity limitation, offering a short-process alternative to energy-costly homogenization for high-performance battery foil manufacturing.