Effects of Silicon and Quasicrystal Contents on the Microstructure and Microhardness of Pressure-Solidified Recycled Aluminum

Recycled aluminum has emerged as an excellent alternative for producing new alloys. The development of multicomponent alloys has led to products with enhanced properties, and the aluminum alloy market has increased. This study utilized squeeze casting to produce Al alloy samples. The effects of 5 wt.% of both the Si content and the Al-25.5 Cu−12 Fe quasicrystal (QC) content on the microstructural formation and microhardness analyzed. A cellular microstructural formation was found for the recycled aluminum. A dendritic structure was characterized in both the Alrec−5% Si and Alrec−5% QC alloys. After adding 5% wt.% QCs, the resulting hardness became higher (varying between 110 and 130 HV) than the alloy with 5 wt.% Si (90 and 110 HV) and the recycled aluminum alloy (between 70 and 80 HV). The portion of the QC alloy completely dissolved into the bulk of the recycled alloy during squeeze casting. This was associated with a more complex phase arrangement characterized by the QC alloy. This was characterized by a dendritic microstructural array with binary eutectic mixtures (α-Al + Mg2Si) and refined ternary eutectic mixtures (α-Al + Mg2Si + AlFe(Si)). In contrast, the sample with Si content and the recycled alloy sample without additions depicted resulting microstructural arrays with reduced secondary phase formations. These contributed to improved mechanical behavior through traditional strengthening mechanisms.