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Common strengthening strategies for casting aluminum alloys sacrifice ductility. Herein, the strength-ductility synergy of a rheo-diecasting semi-solid Al–Si–Mg–Cu–Fe–Sr alloy was tailored by optimizing the pouring temperature and subsequent heat treatment. The results demonstrated that with decreasing pouring temperature from 700 °C to 670 °C, the average grain diameter of primary α-Al grains and porosity decreased, while the average shape factor and solid phase fraction increased, resulting in improved mechanical properties of the alloy. After T6 heat treatment, changes in the morphologies of eutectic Si phases and Al3Fe phases were observed, and Mg2Si precipitates were formed, which further enhanced the mechanical properties of the alloy.

The addition of trace La significantly affected the properties of the Al–Zn–Si coating. Adding La improved the corrosion resistance of the coating. More importantly, it restrained the nucleation of α-Al dendrites consequently leading to coarser grains. Based on the density functional theory calculations, we found that the doping concentration was important to the spontaneous nucleation of the heterogeneous nucleus in liquid metal, and there should be a transition between homogeneous nucleation and heterogeneous nucleation.

Continuous preparation of high-conductivity and high-strength aluminium alloy cable remains a challenge. Here we reveal the scientific significance of high electrical conductivity Al-Ag-Sc-Zr alloy with ultrafine grains prepared by novel processing technologies, the combination of rheo-extrusion and accumulative continuous extrusion forming. Attributed to the continuous dynamic recrystallization during rheo-extrusion, equiaxial microstructure and significantly refined grains (2.8 ± 0.2 μm) were achieved. By means of partially replacing low conductive scandium and zirconium solute atoms with high conductive silver solute atoms, the processed alloy wires exhibit significant higher electrical conductivity (53.5 ± 0.4 %IACS) than the Al-Sc-Zr alloy with similar atomic concentration of alloying elements. Appropriate mechanical properties were also obtained due to the similar solution strengthening effects of silver atoms to scandium and zirconium atoms. These results highlight the potential of this high electrical conductivity Al-Ag-Sc-Zr alloy and its novel processing route.