Simulation Study on the Mechanical Behavior of Copper–Silver Alloy with Twinning-Induced Gradient Segregation

This study employed molecular dynamics (MD) simulation to investigate the mechanical behavior of copper–silver (Cu–Ag) nanocrystalline alloys with twinning structures under solute gradient polarization conditions. The equidistant scaling method was used to identify different regions within the material, such as the solute concentration distribution from the grain interior to the GBs (GBs). MD simulations revealed that adjusting the twinning boundary spacing (TBS) can effectively improve the mechanical properties of Cu–Ag alloys. Tensile tests showed that stretching the twinning boundaries leads to a reduction in stress levels within the alloy. Furthermore, analysis based on the atomic structure volume fraction revealed that larger TBS values result in more pronounced structural changes within the alloy, particularly a significant transition from the face-centered cubic structure to the hexagonal close-packed structure. The latter typically possesses a higher density and closer packing, thus often exhibiting a higher strength and hardness. These findings reveal that adjusting the grain size, segregation gradients, TBS, and grain number can effectively improve the mechanical properties of Cu–Ag alloys.