Approaching 1 GPa ultra‐high tensile strength in a nanostructured Al‐Zn‐Mg‐Cu‐Zr‐Sc alloy prepared by severe plastic deformation

Alloy composition and heat treatment process have limited possibility to enhance ultra‐high strength aluminum alloys, which restricted their widespread application in lightweight equipment. Consequently, high density dislocations and grain refinement were suggested to strengthen ultra‐high strength aluminum alloys. Here, a novel nanostructured Al‐Zn‐Mg‐Cu‐Zr‐Sc (AZMCZS) alloy with homogeneous microstructure and average grain size around 117.7 nm was prepared through the synergistic processing of hot extrusion and high pressure torsion. Additionally, the microstructures and strengthening mechanisms of the nanostructured Al alloy were analyzed. It was observed that ultimate tensile strength of the nanostructured Al alloy reached nearly 1 GPa, and the elongation of the alloy was 1.9%. The nanostructured Al alloy mainly consists of nanoscale grains (～117.7 nm), high density dislocations (2.4×1015 m‐2), nano‐sized precipitates (the size of 20‐51 nm) and solute atom clusters (～3 nm). The multiple strengthening mechanisms of the nanostructured Al alloy were revealed in terms of grain refinement, dislocations, precipitates, and solute atom clusters. Grain refinement and dislocation strengthening showed superior outcomes and were considered to be the predominant strengthening mechanisms. These findings demonstrate that this nanostructural architecture offers a new way to design super‐strength metals and alloys through effectively controlling the processing regime of severe plastic deformation.This article is protected by copyright. All rights reserved.