Microstructural Modulations Enhance the Mechanical Properties in Al–Cu–(Si, Ga) Ultrafine Composites

Abstract Adding small amounts of Si or Ga (3 at.%) to the eutectic Al₈₃Cu₁₇ alloy yields an ultrafine bimodal eutectic composite microstructure upon solidification. The as‐solidified alloys exhibit a distinct microstructural length‐scale hierarchy leading to a high fracture strength of around 1 GPa combined with a large compressive plastic strain of up to 30% at room temperature. The present results suggest that the mechanical properties of the ultrafine bimodal eutectic composites are strongly related to their microstructural characteristics, namely phase evolution, length‐scales, and distribution of the constituent phases.