Dislocation-based strengthening mechanisms in metal-matrix nanocomposites: a molecular dynamics study of the influence of reinforcement shape in the Al-Si system

ZB Zhang and HM Urbassek, COMPUTATIONAL MATERIALS SCIENCE, 145, 109-115 (2018).

DOI: 10.1016/j.commatsci.2017.12.063

We use molecular dynamics simulations to study the interaction of dislocations with reinforcements of various shape during nanoindentation of Al/Si metal-matrix nanocomposites. Three different geometries of the Si reinforcement are considered: a spherical particle, a cylindrical fiber, and a plate. We show that plate reinforcements may absorb dislocations and emit them back into the matrix with altered glide direction, both strengthening and toughening the composite, in agreement to experiment. This mechanism does not work for spherical reinforcements, since the curved interface does not allow for dislocation emission; the case of fibers is intermediate. It is concluded that the shape of the reinforcement plays a dominant role in dislocation-based strengthening mechanisms in metal-matrix nanocomposites. (C) 2017 Elsevier B.V. All rights reserved.

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