Enhanced Thermal Stability of Nanocrystalline Cu-Al Alloy by Nanotwin and Nanoprecipitate

The structural stability of nano-grained Cu-Al alloy synthesized by ball milling under liquid nitrogen temperature was analyzed. The hardness of the alloy drops only 6 % after annealing at 1173 K for 30 min, in comparison to the as-milled condition. X-ray diffraction (XRD), transmission electron microscopy (TEM), and Molecular dynamics (MD) simulation was incorporated to get an insight into the enhanced thermal stabilization of the alloy. Cryogenic ball milling introduces extensive deformation twins in the micro-structure and a significant amount of twins are present after annealing. The retained nanoscale twins along with the annealing induced Al2Cu nano-precipitate synergistically contribute toward the structural stability of the alloy. (C) 2022 Elsevier B.V. All rights reserved.