Microstructure evolution, thermal conductivity and mechanical properties of hot-rolling Al-Si-Fe-Mg alloy under different reductions

To further improve the properties of the Al-11.5Si-0.4Fe-0.35Mg, the effects of different reductions of hot-rolling (HR) Al-Si-Fe-Mg alloy on microstructure, thermal conductivity (TC), and mechanical properties were investigated in this paper. The results show that the eutectic silicon phases are broken and moved during the HR process. The average size of eutectic silicon phase decreases. Meanwhile, the aspect ratio of eutectic silicon phase closer to 1 and the distribution of that are more uniform with the increase of HR reduction. In addition, the ternary Al-Fe-Si phases are also broken after HR. It indicates that the action of shear force induced by the HR process is beneficial to promote refinement and spheroidization of the eutectic silicon phase, hence further improves the properties of the alloy. Apparently, the fine and dispersed distribution of spherical silicon particles can minimize the splitting of the alpha-Al matrix, decrease the scattering effect on free electrons, and increase the number of free-electron transport channel. Therefore, the overall performance of HR Al-Si-Fe-Mg alloy with a reduction of 71.25% is the best with the TC of 170.24 W/m . K, the tensile strength of 241.98 MPa and elongation of 8.73%, respectively.