Strengthening and toughening mechanisms of amorphous/amorphous nanolaminates

• Tensile deformation of amorphous/amorphous nanolaminates are investigated.
• The strength of the nanolaminates increase with decreasing the layer thickness.
• The plastic mechanism transit from localized shearing to homogenous deformation.
• Multiple shear bands interaction contribute to ductility and cause plastic plateaus.
• A model on the critical size for the controlling mechanism transition is proposed.

Bulk amorphous alloys are in general strong, but brittle. Properly introduced interfaces can effectively improve their ductility. In this paper, the tensile behavior of amorphous/amorphous (A/A) nanolaminates is investigated by atomistic simulations. Upon loading, multiple shear bands transmit through the A/A interfaces and interact with each other. As a result, plastic plateaus are presented in the simulated tensile stress–strain curves of the nanolaminates with small layer thickness. Moreover, the strength of the A/A nanolaminates increases with the layer thickness decreasing, due to the interface obstruction to the shear band motion. It is also found that the plastic deformation mechanisms transit from localized shearing in the soft amorphous layers to multiple shear band interactions in the whole sample at a critical size. An analytical model considering shear band motion is proposed to predict the critical layer thickness for the localized to homogenous deformation transition in A/A nanolaminates.