Synergetic effect of graphene nanoplatelets (GNPs) and multi-walled carbon nanotube (MW-CNTs) on mechanical properties of pure magnesium

•The Mg-graphene/CNTs composites are fabricated in present work.•Synergetic effect of MW–CNTs and GNPs in magnesium matrix is investigated.•MW–CNTs intercalates between Graphene sheets to form 3D hybrid structures. Graphene nanoplatelets (GNPs) are novel reinforcing fillers due to their fascinating mechanical properties. However, their unique mechanical properties rapidly devolve as the sheets aggregate due to strong van der Waals forces and π–π attractions, therefore limiting their applications in metal matrix composites. In present work, the rapid aggregation of two-dimensional GNPs is inhibited by intercalating one-dimensional multi-walled carbon nanotubes (MW-CNTs). The long and flexible MW-CNTs bridge adjacent GNPs to form three dimensional hybrid structures which prevent their aggregation, thus resulting in a high contact area between CNTs+GNPs hybrid structure and the matrix. The composite reinforced with hybrid (GNPs and CNTs) reinforcement exhibited higher failure strain than those reinforced with individual GNPs and MW-CNTs. Compared to pure Mg, the Mg–1Al–0.6wt.%(CNTs+GNPs) composite exhibited improvement in elastic modulus, 0.2% yield strength, ultimate tensile strength and failure strain (+17%; +19%; +15% and +137%, respectively). The impressive increase in tensile failure strain (%) confirmed significant synergetic effect between GNPs and MW-CNTs.