Development of AZ91D magnesium alloy-graphene nanoplatelets composites using thixomolding process

Abstract

Graphene nanoplatelets (GNPs) have been considered as ideal nano-reinforcements for magnesium matrix composites (MMCs) owing to their excellent mechanical properties. It is necessary to develop efficient fabrication method for reality application of GNPs reinforced MMCs. Here, AZ91D magnesium alloy-graphene nanoplatelets (AZ91D-GNPs) composites were fabricated by thixomolding process for the first time. OM, SEM, EDS, HRTEM, XRD, and Raman spectroscopy were used for characterization of the composites. GNPs were well-dispersed in the Mg matrix and a strong interfacial bonding had been formed between GNPs and alloy matrix. Based on response surface methodology, quadratic prediction models had been developed for the ultimate tensile strength (UTS), elongation (δ), Vickers hardness (HV) and porosity (P) of composites, respectively. The interaction effects between two explanatory variables, the content of GNPs (C) and the barrel temperature (TB), on microstructure and mechanical properties of composites were investigated using dimensional response surface. The optimization for thixomolding process was investigated using “Numerical optimization process”. The optimal UTS, δ, HV and P achieved for AZ91D-GNPs composites were 38.4%, 85.7%, 29.9%, and 33.3% higher than those obtained for AZ91D magnesium alloy, respectively. The utilized preparation technology is a very promising technique for mass-scale production and application of GNPs reinforced MMCs.