Mechanical behavior of sintered cross-shaped fivefold twinned Ag nanowires: Insights from a molecular dynamics study

This study presents a molecular dynamics (MD) investigation of the sintering behavior and mechanical properties of cross-shaped silver (Ag) fivefold twinned nanowires (FTNWs). A model of two FTNWs arranged at 90° intersections was constructed and sintered at three temperatures (698, 898, 1098 K) with three heating rates (1.0, 0.1, 0.01 K/ps), followed by high-temperature relaxation and controlled cooling at 0.08 K/ps. After cooling, room-temperature relaxation was performed in the isothermal-isobaric ensemble using different time durations and reinitialized with different random seeds to ensure statistically independent velocity distributions and structural equilibration. Uniaxial tensile tests were then carried out at strain rates of 1.0 × 10^- 3, 5.5 × 10^- 4, and 1.0 × 10^- 4 ps^- 1. Effects of sintered temperature, heating rate, relaxation duration, and strain rate on yield strength were systematically analyzed. The results show that FTNWs sintered at lower temperature and higher heating rate tend to attain higher yield strength, attributed to limited atomic diffusion, which preserves the pre-existing fivefold twin boundaries (TBs) and structural integrity along the central axis. Additionally, higher strain rates yield greater tensile strength, while lower ones result in reduced strength. During deformation, FTNWs undergo nucleation and propagation of multiple stacking faults (SFs) that evolve into TBs and can eventually form a pair of quasi-icosahedral structures during necking and fracture; this mechanism consistently links to the formation of secondary fivefold twins around the original axis. For comparison, cross-shaped single-crystalline nanowires (SCNWs) were simulated under identical conditions: they exhibit ~ 18% lower yield strength but demonstrate markedly greater ductility (fracture strain is 4.5 times that of FTNWs), without showing any development of quasi-icosahedral structures during the tensile deformation.

The online version contains supplementary material available at 10.1007/s00339-026-09778-7.