The quantitative analysis of the crack propagation on the fatigue properties of dual-phase approximate equiaxial nanocrystalline AgCu alloy

Nanostructure dual-phase equiaxial alloy (DPEA) possesses the unique mechanical properties of high strength and ductility. However, the investigation of the fatigue properties in DPEA remains to be solved. In this paper, the mechanism of fatigue crack propagation in DPEA is explained by the interaction between dislocations and clusters in different grains of materials. The stress of dislocations on the slip plane and the time constant of pinned dislocation bypass the cluster can be calculated. The results show that the presence of clusters results in dislocations on the slip planes to induce different degrees of pile-up. The pile-up of dislocations is the dominant factor for hindering crack growth, which facilitates the crack blunting and improves the fracture toughness of alloy, during the plastic deformation of materials. In addition, based on the calculated results of the theoretical model, it is revealed that fracture toughness of DPEA is sensitive to the grain size, activation energy and the time constant of dislocation bypass the cluster. In a word, this research has provided a rational framework to amply explain the fatigue properties of DPEA based on theoretical model.