Microalloying effect on the microstructure and mechanical properties in Al–Cu based dendrite-ultrafine composites

Microalloying effect of Sn or Ge (1 at.%) on the microstructure and mechanical properties of the hypo-eutectic Al86Cu14 alloy has been investigated. The (Al86Cu14)99(Sn and Ge)1 alloys exhibit a high fracture strength of 0.85 GPa and a large compressive plastic strain of ∼10% at room temperature. The present results suggest that the minor addition of elements having immiscibility (Sn) or extremely limited solubility (Ge) with the main constituent element (Al) in the Al–Cu based dendrite-ultrafine composites has a strong influence on the microstructural evolution of eutectics such as phase constitution, distribution and colony morphology, leading to improve the compressive plasticity.

► Al-based dendrite-ultrafine eutectic composites with good mechanical performance have been developed by the micro-alloying.
► The (Al86Cu14)99(Ge)1 alloys exhibit a high fracture strength of 0.85 GPa and a large compressive plastic strain of ∼10%.
► The enhanced plasticity in Ge containing alloy is attributed to the combined effect of length scale heterogeneity.