Strengthening and softening in gradient nanotwinned FCC metallic multilayers

Abstract

The plastic-deformation behaviors of gradient nanotwinned (GNT) metallic multilayers are investigated at the nanoscale via molecular dynamics simulation. The evolution law of deformation behaviors of GNT metallic multilayers with different stacking fault energies (SFEs) during nanoindentation is revealed. The deformation behavior transforms from the dislocation dynamics to the twinning/detwinning in the GNT Ag, Cu, to Al with SFE increasing. In addition, it is found that the GNT Ag and GNT Cu strengthen in case of a larger twin gradient based on more significant twin boundary (TB) strengthening and dislocation strengthening. But the GNT Al softens due to more TB migration and dislocation nucleation from TB at a larger twin gradient. The softening mechanism is further analyzed theoretically. These results not only provide an atomic insight into the plastic-deformation behaviors of certain GNT metallic multilayers with different SFEs, but also give a guideline to design the GNT metallic multilayers with required mechanical properties.

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

“…Molecular dynamics (MD) simulation provides an alternative method to experiments, which plays an important role in understanding the deformation mechanism in metallic materials. [35][36][37][38] Actually, the mechanical properties of the crystalline/amorphous nanolaminates have been investigated in the past few years using MD simulation. [39][40][41][42] Tran and Fang [39] reported that the plastic deformation zones increase as the thickness of each layer decreases in crystalline/amorphous Cu/CuTa nanolaminates.…”