The Ag-Cu alloys have received attention due to their excellent electrical and mechanical properties. However, the analytical research on why the mechanical properties of the Ag-Cu alloys increase after a small amount of Cu atoms are added is still lacked. In this work, the classical molecular dynamics (MD) simulations method was used to establish the Ag-Cu alloy models with different Cu contents. The tensile deformation mechanism of Ag-Cu alloy at room temperature was revealed from the atomic scale through the analysis of the stress-strain behavior and the evolution of dislocations. During the simulations, the embedded atom method (EAM) potential was used to describe the interaction between Ag atom and Cu atom. The uniaxial tensile deformation and nanostructure evolution of Ag-3 at.% Cu, Ag-6 at.% Cu and Ag-10 at.% Cu alloy models at the temperature of 300 K and the strain rate of 0.02 Å/ps were studied in detail. Results show that the internal stress was generated due to the large lattice mismatch among Ag atom, Cu cluster and the grain boundary. It results in the formation of dislocation and the negative initial stress at the beginning stage of Ag-Cu alloy models under tension. The dislocation firstly nucleates at the grain boundary and the growth rate of dislocation is slow before the crack propagation, and the complex dislocation reactions also exist. With the increase of Cu content, the tensile strengths of Ag-Cu alloys also increase. Cracks mainly form at the intersection of multiple grains, and the fracture mode changes from the intergranular fracture to the intergranular fracture and transgranular fracture after the unstable propagation of cracks. Meanwhile, a plenty of Cu atoms are distributed in the form of clusters in Ag matrix. They hinder the slip of dislocation and slow the relative sliding between atomic layers, and thus finally improves the deformation resistance to the plastic deformation of Ag-Cu alloy. The study on the tensile deformation behavior of Ag-Cu alloy at room temperature has certain guiding significance for the practical production and application of the design of Ag-Cu alloy.
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