Role of amorphous layer and interfaces on the tensile behaviors of triple-phase Ti/Ni nanolaminates: A molecular dynamics study

Abstract

Abstract Superior properties of Ti/Ni nanolaminates prompt researchers to comprehend their mechanical behaviors deeply. Lacking investigations at several nanometers range limits their applications in high-precision fields, as the amorphous phase can be formed at the junction regions. By using the molecular dynamics method, three models are chosen to investigate the role of the amorphous layer and different interfaces in triple-phase Ti/Ni nanolaminates during the tensile process. The results demonstrate that mechanical performances of triple-phase nanolaminates are closely related to the fraction of crystalline and amorphous phases. Strength of the nanolaminates decreases with increasing amorphous layer spacing (d). However, acceptable plastic properties can be achieved when amorphous layer spacing satisfies d ≤ 3.91 nm. Microstructure evolution analysis reveals different plastic deformation carriers nucleate and propagate in crystalline and amorphous layers, which contains grain reorientation and basal dislocation propagation in Ti layer, partial dislocations propagation in Ni layer, formation and expansion of shear transformation zones in the amorphous layer. Plastic co-deformation of dissimilar phases dominates the plastic deformation of triple-phase nanolaminates. Crystalline/crystalline interfaces (CCIs) and amorphous/crystalline interfaces (ACIs) also play vital roles in plastic deformations. CCIs impede and absorb the grain boundaries moving toward the interfaces and then act as dislocation sources. ACIs accommodate local deformation at the interfacial regions, and are preferred sites for different plastic deformation carries nucleation. ACIs and CCIs can also connect the plastic deformation carries in different phases, which improves the overall plasticity of triple-phase nanolaminates. The insights obtained in this work can promote the design and application of advanced Ti/Ni nanolaminated materials.