Molecular dynamics study on the tensile behaviors of triple-phase Ti/Ni nanolaminates: size and temperature dependence

Metallic nanolaminates subjected to alloying treatment exhibit superior physical and chemical properties compared to the as-deposited nanolaminates. However, how the intermetallic compound phase affects the mechanical behaviors of the materials remains inadequately understood. In this work, the molecular dynamics method is employed to evaluate the effect of intermetallic compound layer spacing ( d ) and temperature ( T ) on the mechanical behaviors of triple-phase Ti/Ni nanolaminates. Size and temperature dependent tensile behaviors of triple-phase materials are discovered during the loading process. Both yield strength and flow stresses decrease with increasing intermetallic layer spacing and temperature. The plastic deformations of matrix phases are seldom affected by temperature variations, whereas the plastic deformations of intermetallic compound phases and interfaces are very sensitive to temperature and layer spacing. At 300 K, plastic deformations in intermetallic compound layers with the minimum size are dominated by martensitic transformation and amorphization of the compounds. In contrast, the intermetallic compound layers in other samples undergo rapid martensitic transformation and serve as the elastic supporting roles during subsequent loading processes. The more complex plastic deformations of intermetallic compound layers are discovered at 600 K. After the initial martensitic transformation, amorphization of intermetallic compound phase prevails at d = 1.279 nm, amorphization accompanied by the shear bands occurs at intermediate layer spacing (1.279 nm < d < 11.939 nm), and twinning deformation at larger layer spacing ( d ≥ 11.939 nm) dominates the plastic deformations of intermetallic compound layers. Furthermore, the interfaces accommodate plastic deformations of different phases through interface diffusion or sliding, in which their deformation coordinating capability is enhanced at elevated temperature. The conclusions from this work can provide the micro-mechanistic insights for the design and development of high-performance metallic nanolaminates.