Influence of pre-existing stacking fault on the mechanical and microstructural behavior of Cu–Zn alloys—a molecular dynamics study

Abstract This study explores the impact of pre-existing stacking fault defects on the mechanical behavior and microstructural evolution of Cu–Zn alloys under uniaxial tensile loading through Molecular Dynamics (MD) simulations. It further examines the influence of varying zinc concentrations (6 at %, 12 at %, and 24 at %) on the alloy’s mechanical properties. The MD simulations are used to evaluate key mechanical parameters, including Young’s modulus, ultimate tensile strength (UTS), and toughness. A detailed comparison of these properties is carried out to identify inherent trends associated with changes in composition. Additionally, the temperature dependence analysis conducted over the range of 200 K to 800 K shows that higher temperatures accelerate failure, reduce UTS, and lower toughness, while system size has a stabilizing effect on stress–strain response. Zn concentration further amplifies these effects, particularly in alloys with pre-existing stacking faults. Complementary to these analyses, Common Neighbor Analysis (CNA) is performed to investigate atomic structural changes within the predominantly FCC solid solution under varying conditions. The results indicate that increasing Zn content in defect-free Cu–Zn alloys leads to a decline in mechanical performance. However, the introduction of pre-existing stacking faults results in a reduction in UTS but an increase in Young’s modulus, suggesting improved resistance to elastic deformation.