Influence of the Final Annealing Temperature on Al-Fe-Si Alloy Foil Microstructure and Properties

This study systematically investigates the effects of the final annealing temperature on the microstructural evolution and mechanical properties of an Al-Fe-Si alloy aluminum foil. Scanning electron microscopy (SEM) characterization and tensile tests are employed for analysis. As the annealing temperature is elevated from 240°C to 360°C, the average grain size increases monotonically from 5.2 μm to 9.6 μm. Continuous recrystallization is identified as the predominant grain growth mechanism.Tensile deformation exhibits the homogeneous-plastic behavior without localized necking. The tensile strength decreases significantly in the range of 240–300°C and subsequently undergoes a recovery stage at 300–360°C. The Pronounced elongation anisotropy is observed. The maximum elongation reaches 30–34% along the 45° direction relative to the rolling direction (RD), which is approximately 1.5 times that along the RD (0°).Comparative analysis of the anisotropy indices demonstrates that the aluminum foil annealed at 240°C achieves the minimal tensile strength anisotropy (13.0 MPa) and elongation anisotropy (−4.2%). This indicates optimal comprehensive mechanical performance.These findings provide a theoretical rationale for the industrial optimization of the annealing processes for Al-Fe-Si alloy foils. They are particularly valuable for balancing microstructural regulation and mechanical property enhancement in lithium-ion battery soft-packaging applications.