Effect of solid solution and vacancies on the mechanical properties of Cu (Al)/Al₂Cu/(Cu)Al layered gradient heterostructures

We used molecular dynamics simulation (MD) methods to investigate the effect of diffused solutes and vacancies on the tensile deformation behavior of nano-polycrystalline Cu(Al)/Al2Cu/(Cu)Al layered heterostructures. Simulation results show that the Cu(Al)/Al2Cu/(Cu)Al layered heterostructure with Al-20% Cu has the highest ultimate strength and fracture strain. On this basis, gradient Cu solute in the matrix Al improves the synergistic tensile deformation behavior among the components of the nano-polycrystalline Cu(Al)/Al2Cu/(Cu)Al layered gradient heterostructure. More importantly, gradient Cu solute contributes to the localized strain transfer between component layers, ultimately increasing the fracture strain and ultimate strength. In addition, deformation behavior between polycrystalline Cu(Al)/Al2Cu/(Cu)Al layered gradient heterostructure fails at low tensile strains because the vacancies cause strain concentration of polycrystalline Cu near the interface and weaken strain delocalization in polycrystalline Al.