The effect of heat treatment and cooling conditions on friction stir processing of A390-10 wt% SiC aluminium matrix composite

In the present study, SiC particle reinforced hypereutectic Al?Si alloy composites were produced from semi-solid casting and friction stir processing (FSP). The study aimed to evaluate the effect of pre-and post-processing heat treatments and cooling conditions during FSP. Based on the results, FSP led to the formation of a completely uniform, fine equiaxed, and recrystallized grain microstructure in the as-cast composite. In addition, the presence of a large number of reinforcing particles, such as Si and SiC, enhanced the thermal stability of the recrystallized microstructure and inhibited the abnormal growth of the equiaxed grains after the heat treatment of friction stir processed (FSPed) composites. Further, adding SiC reinforcing particles to the A390 aluminium alloy after the three-pass FSP resulted in an increase of 23 and 68% in tensile strength and toughness, respectively. The results indicated that FSP and then post artificial aging heat treatments increased the tensile strength and toughness of the as-cast composite by 55 and 227%, respectively.

Automated summary

The study demonstrated that producing SiC particle reinforced hypereutectic Al-Si alloy composites using FSP resulted in a uniform microstructure, enhanced thermal stability, and increased tensile strength and toughness. The addition of reinforcing particles inhibited abnormal grain growth and post artificial aging heat treatments further improved the mechanical properties of the composites.