Deformation mechanism of bimodal nanotwinned Cu-Ag alloy with grain boundary affect zone segregation

The deformation mechanism of bimodal nanotwinned (NT) Cu-Ag alloys with grain boundary affect zone (GBAZ) segregation has been investigated through molecular dynamics (MD) simulations. The bimodal NT Cu-Ag alloys model is established by embedding a coarse NT grain into the ultrafine grained matrix. The solute Ag atoms in Cu-Ag alloy polycrystalline matrix are segregated in the GBAZ (generated by equidistance scaling method). The coarse NT grain inclusion phase can impart high strength resulting from the twin boundaries (TB) strengthening regime. Through the uniaxial tensile simulations, the strength of bimodal NT samples is found to be related with the three factors, including coarse NT grain size, TB inclination angles as well as TB spacings (TBSs). The dislocation activities and corresponding deformation mechanisms are explored in detail.