Synthesis of graphene oxide reinforced ZK60 magnesium matrix composite with high ductility via powder thixoforming

The poor ductility of Mg alloys, especially Mg alloy-based composites, is still a critical factor restricting their applications and development. In the present work, graphene oxide (GO) reinforced ZK60 Mg matrix composites were fabricated via powder thixoforming. The results indicate that a dense microstructure with homogeneous distribution of GO can be successfully achieved by powder thixoforming when the incorporated GO content is not over 0.1 wt%. Compared with the ZK60 matrix alloy, the composite with 0.1 wt% GO possesses 19% enhancement in yield strength up to 156 MPa and a high elongation of 22.3%, exhibiting a high strengthening efficiency of 239 and almost a same elongation to that of the matrix alloy, i.e., the trade-off between strength and ductility has been well overcome. The good ductility is contributed to the long uniform-elongation period with a relatively high strain hardening rate. The improvement in tensile strength is due to grain refinement strengthening, load transfer strengthening and thermal mismatch strengthening. This study suggests that the powder thixoforming method used in this work is a promising technology to fabricate GO/graphene reinforced metal based composites with high performance.