Hierarchical ultrafine-grained/nanocystalline Al-based bulk alloy with high strength and large plasticity

An in-situ ultrahigh-strength ductile Al-based bulk alloy was produced by copper mold casting method. According to the microstructural investigations, ultrafine-grained/nanocrystalline eutectic colonies with length-scale heterogeneity of lamellar structure have been observed, besides few primary Ag51Y14 phase with a size scale of 1–5 μm. The macroscopic and microscopic structural heterogeneities are able to achieve high strength of up to 1.24 GPa and large compressive plasticity of ∼26%, which is considered to be attributable to the hierarchical network of strengthening intermetallic phases combining with deformable α-Al solid solution suppressing the propagation of microcracks or shear bands.