An atomistic study of deformation mechanisms in metal matrix nanocomposite materials

With nanoscale reinforcements resulting in a high density of matrix/reinforcer interfaces, metal matrix nano -composite (MMNC) materials behave differently from their micro-composite counterparts. An atomistic level understanding of the fundamental deformation mechanisms is necessary to link the nanoscale reinforcement attributes with the strengthening and fracture properties of the nanocomposite. Using the Aluminum-(Silicon Carbide), Al-SiC, nanocomposite as an example, we conducted classical Molecular Dynamics simulations of uniaxial tensile deformation for the composite. By varying nanocomposite design parameters, including the SiC particle size, and the particle volume fraction, we revealed the deformation mechanisms and defects evolution in nanocomposite materials. The deformation mechanisms are characterized into three subsequent mechanisms, which are (I) defect-free deformation driven by lattice distortion of the matrix, (II) dislocation-based deformation driven by dislocation nucleation and growth, and (III) failure-based deformation driven by interface separation and void growth. The nanoparticle volume fraction was found to have a major effect on dislocation-based deformation, whereas the particle size had a greater impact on the failure-based deformation. This work sheds light on the fundamental deformation mechanisms of MMNCs which may facilitate the future design of advanced nanocomposites with broader applications.