High-strength bulk Al-based bimodal ultrafine eutectic composite with enhanced plasticity

Abstract

An in situ bulk ultrafine bimodal eutectic Al–Cu–Si composite was synthesized by solidification. This heterostructured composite with microstructural length scale hierarchy in the eutectic microstructure, which combines an ultrafine-scale binary cellular eutectic (α-Al + Al2Cu) and a nanometer-sized anomalous ternary eutectic (α-Al + Al2Cu + Si), exhibits high fracture strength (1.1 ± 0.1 GPa) and large compressive plastic strain (11 ± 2%) at room temperature. The improved compressive plasticity of the bimodal-nanoeutectic composite originates from homogeneous and uniform distribution of inhomogeneous plastic deformation (localized shear bands), together with strong interaction between shear bands in the spatially heterogeneous structure.