Achieving highly strengthened Al-Cu-Mg alloy by grain refinement and grain boundary segregation

TL;DR

This study demonstrates that high-pressure torsion and aging significantly enhance the strength of Al-Cu-Mg alloy through microstructural refinement and solute segregation at grain boundaries, achieving near 1 GPa tensile strength.

Contribution

It introduces a combined process of HPT and aging to produce ultrafine-grained Al-Cu-Mg alloy with unprecedented strength, highlighting the role of grain boundary segregation.

Findings

Tensile strength reached ~1 GPa after processing.

Segregation of solutes at grain boundaries enhances strength.

Multiple hardening mechanisms contribute to the high strength.

Abstract

An age-hardenable Al-Cu-Mg alloy (A2024) was processed by high-pressure torsion (HPT) for producing an ultrafine-grained structure. The alloy was further aged for extra strengthening. The tensile strength then reached a value as high as ~1 GPa. The microstructures were analyzed by transmission electron microscopy and atom probe tomography. The mechanism for the high strength was clarified in terms of solid-solution hardening, cluster hardening, work hardening, dispersion hardening and grain boundary hardening. It is shown that the segregation of solute atoms at grain boundaries including subgrain boundaries plays a significant role for the enhancement of the tensile strength.