Layer thickness dependent plastic deformation mechanism in Ti/TiCu dual-phase nano-laminates

Abstract

Crystalline/amorphous nanolaminate is an effective strategy to improve the mechanical properties of metallic materials, but the underlying deformation mechanism is still under the way of exploring. Here, the mechanical properties and plastic deformation mechanism of Ti/TiCu dual-phase nanolaminates (DPNLs) with different layer thicknesses are investigated using molecular dynamics simulations. The results indicate that the influence of the layer thickness on the plastic deformation mechanism in crystalline layer is negligible, while it affects the plastic deformation mechanism of amorphous layers distinctly. The crystallization of amorphous TiCu is exhibited in amorphous parts of the Ti/TiCu DPNLs, which is inversely proportional to the layer thickness. It is observed that the crystallization of the amorphous TiCu is a process driven by stress and heat. Young’s moduli for the Ti/TiCu DPNLs are higher than those of composite material due to the amorphous/crystalline interfaces. Furthermore, the main plastic deformation mechanism in crystalline part: grain reorientation, transformation from hexagonal-close-packed-Ti to face-centered cubic-Ti and body-centered cubic-Ti, has also been displayed in the present work. The results may provide a guideline for design of high-performance Ti and its alloy.