Atomistic simulations of nano-fiber-confined metal plasticity

Abstract

Atomistic simulations are used to explore dislocation mechanisms in nano-confined aluminium (Al) containing silicon (Si) nanofibers. Our simulations revealed that dislocations on four {111} slip planes nucleate at Al-Si interfaces, propagate in Al nano-channels, loop and bow around Si nanofibers. Due to multiple active slip systems and dislocation cross-slips in the confined volume, a high density of dislocations intersects to form dislocation junctions and promote the formation of dislocation forests, resulting in high flow strength and strain hardening. The plasticity of Si nanofibers is accommodated by local shears and fracture triggered by the accumulated dislocation loops. Simulations show that the cracking of Si nanofibers can be efficiently buffered by dislocation mobility in the surrounding Al. Our results are consistent with experiments on nano-fibrous Al-Si eutectic microstructure.