Tensile and nanoindentation deformation of amorphous/crystalline nanolaminates: Effects of layer thickness and interface type
WR Jian and L Wang and XH Yao and SN Luo, COMPUTATIONAL MATERIALS SCIENCE, 154, 225-233 (2018).
We perform molecular dynamics simulations to investigate plastic deformation of alternative Cu64Zr36/Cu amorphous-crystalline nanolaminates (ACNLs) with different layer thicknesses and interface types under uniaxial tension and nanoindentation. Plastic deformation is characterized by shear transformation zones (STZs) or shear bands in amorphous layers and dislocations in crystalline layers, respectively. Nucleation of STZs or shear bands in an amorphous layer can be triggered at glass-glass interfaces (GGIs) in the same layer or at the intersections of amorphous-crystalline interfaces (ACIs) and dislocations from the neighboring Cu layers. Decreasing layer thickness and introducing grain boundaries (GBs) or GGIs into ACNLs are effective methods to improve ductility and facilitate the transition from inhomogeneous deformation to homogeneous deformation or co-deformation. With the decrease of layer thickness, more ACIs are introduced and behave as nucleation sites of STZs and dislocation. These STZs at the adjacent interfaces can interact with each other directly, promoting the deformation transition. Additionally, the introduction of GBs and GGIs facilitates crystal plasticity and glass plasticity in corresponding layers, which again boosts the plasticity of nearby layers and contributes to homogeneous strain distribution and co-deformation. However, the improved ductility of ACNLs is at the price of strength and hardness. Thus, keeping a balance among them can be useful for the synthesis of novel nanolaminate with superior ductility, high strength and high hardness.
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