The effect of multi-stage rolling on microstructure and mechanical-functional property evolution in a conductive Al-4Si alloy

Conductive aluminum alloy materials are widely used, driving demand for better synergy between structural and functional properties. In this study, multi-stage rolling refined the microstructure and synergistically optimized the mechanical properties and electrical conductivity (EC) of the Al-4Si alloy. Results showed that multi-stage rolling enabled the ARB-C sample to reach a yield strength (YS) of 201.8 MPa and an EC of 57%IACS (an increase of 149.8 MPa and 11.2%IACS compared with the as-cast state). This significantly improved the strength-EC trade-off of the cryogenic rolling (CR) sample. Mechanism analysis revealed that dislocation strengthening was the main reason for the alloy’s YS improvement, contributing 55% of the total YS. Meanwhile, the texture transition from β-fibers to α-fibers (Brass texture and Goss texture) favored stable sheet forming. Deformation twins within eutectic Si ensured the alloy’s plasticity. The eutectic Si phase dispersed and preferentially nucleated solute Si atoms. Si nanoprecipitates maintained a good coherent relationship with the matrix. These microstructural evolutions were the primary factor reducing the alloy’s electrical resistivity. Overall, multi-stage rolling successfully improves both the alloy’s mechanical properties and EC. It provides a practical pathway to develop highly alloyed, non-heat-treatable aluminum alloys with integrated structural and functional performance.