Grain boundary-assisted deformation in graphene-Al nanolaminated composite micro-pillars

Micro-pillars with diameters varying from 0.5 to 3.5 mu m were fabricated from bulk nanolaminated graphene (in the form of reduced grapheme oxide, RGO)-Al composite. Upon uniaxial compression, the pillar strengths exhibited no obvious size effect, and the pillars of larger diameters possessed smoother stress-strain response, as opposed to the jerky deformation of their smaller counterparts. A corresponding transition in the deformation mode from Al layer extrusion to shear fracture over decreasing pillar diameter was observed. These observations were explained by the competing effect of dislocation accumulation and annihilation, and a grain boundary-assisted deformation mechanism. IMPACT STATEMENT The transition in the deformation mode of graphene-Al composite micro-pillars from localized shear facture to Al layer extrusion over increasing pillar diameter is attributed to a grain boundary-assisted deformation mechanism.