The 1.85 GPa AlSc Bulk Alloy with Abundant Nanoscale Growth Twins**Supported by the Scientific Research Foundation of Xi'an University of Technology under Grant No 101-451115007, the National Basic Research Program of China under Grant No 2007CB613900, the National Natural Science Foundation of China under Grant No 51174161, and the Pivot Innovation Team of Shaanxi Electric Materials and Infiltration Technique under

Abstract

An in situ ultrahigh-strength ductile Al50Sc50 bulk alloy is produced by the copper mold casting method with a composite microstructure of micron-/submicron-sized grains and nanoscale twins. According to the microstructural investigations, hierarchical nanotwinned lamellar AlSc bundles with embedded micron-/submicron-sized Al2Sc and AlSc2 are observed. The as-cast alloy displays a unique act of ultrahigh strength of ∼1.85 GPa together with pronounced work hardening and a large plasticity of ∼14%. Further microstructural investigations on deformed specimens indicate that abundant hierarchical nanotwinned lamellar AlSc bundles are effective to dissipate localization of shear stress or block dislocations from spreading throughout the alloy and hinder the propagation of microcracks formed by local stress transition.