The phase composition, structure and hardening of alloys in the aluminium corner of the AleCaeSc
system were studied in the range up to 10% Ca and up to 1% Sс. The experimental study (optical, scanning
and transmission electron microscopy with electron-microprobe analysis, differential thermal analysis
and hardness measurements) was combined with Thermo-Calc software simulation for the optimization
of the alloy composition. It was shown that only phases of the binary systems (Al4Ca и Al3Sc) might be in
equilibrium with the aluminium solid solution. It was shown that the (Al) þ Al4Ca eutectic had a much
finer structure as compared with the AleSi eutectic, which suggests a possibility of reaching higher
mechanical properties as compared to commercial alloys of the A356 type. The influence of the annealing
temperature within the range up to 600 С on the structure and hardness of the AleCaeSc experimental
alloys was studied. It was determined that the maximum hardening corresponded to the annealing at
300 С, which was due to the precipitation of Al3Sc nanoparticles with their further coarsening. With an
example of an Al-7.6% Ca-0.3% Sc model experimental alloy, a principal possibility of manufacturing
aluminium casting alloys based on the (Al) þ Al4Ca eutectic was demonstrated. Unlike commercial alloys
of the A356 type, the model alloy does not require quenching, as hardening particles are formed in the
course of annealing of casting.