Improving thermal stability and Hall-Petch breakdown relationship in nanocrystalline Cu: A molecular dynamics simulation study

摘要

Nanocrystalline metals suffer from grain growth and breakdown of the Hall-Petch-type strengthening below 20 nm due to a shift in the fundamental deformation mechanisms. Here, we designed a novel columnar nanocrystalline Cu specimen with solely coincidence site lattice (i.e., CSL E3 and E9) grain boundaries that simultaneously exhibits exceptional thermal stability and mitigates the Hall-Petch breakdown using molecular dynamics simulations. Moreover, the CSL GBs enabled continuous enhancement in strength with decreasing grain size in this specimen thus mitigating the Hall-Petch breakdown phenomenon. We believe that this study can aid in the design of ultra-strong and stable nanocrystalline metals with advanced mechanical and structural properties.