Ultimate Strength of Nanotwinned Face-Centered Cubic Metals

In this work, we present a theoretical model to predict the ultimate strength of nanotwinned face-centered cubic (fcc) metals based on the activation energy for phase transformation (i.e., between the matrix and the twinned counterpart) mediated by the migration of ${112}$-type step on $\mathrm{\ensuremath{\Sigma}}3(111)$ twin boundaries. By integrating the Hall-Petch strengthening and grain boundary sliding into this model, we can accurately predict the strength of four representative nanotwinned (nt) fcc metals (nt-Cu, nt-Ag, nt-Ni, and nt-Al) within a broad range of grain sizes including the so-called nanocrystalline-nanotwinned regime. This framework is built on material parameters which directly connect the theoretical calculations with experimental measurements and reveals new insights into the design of ultrastrong metals and alloys.