Simultaneously improved mechanical and thermal properties of Mg-Zn-Zr alloy reinforced by ultra-low content of graphene nanoplatelets

Mg-Zn-Zr (ZK60) alloys reinforced by ultra-low content (< 0.1 wt%) of graphene nanoplatelets (GNPs) were fabricated via stirring cast and extrusion processes. In composites, GNPs thoroughly dispersed and continuously combined with Mg matrix at the interface, beneficial for the load and heat transfer of composites. The static and dynamic mechanical properties of GNP/ZK60 composite were investigated and respectively compared with those of ZK60 alloy. With only 0.04 wt% addition, GNP nanofillers improved the impact toughness twice that of ZK60 matrix up to 17 J cm(-2). In tensile test, GNP(0.04)/ZK60 composite performed enhanced tensile yield strength of 256 MPa, improved by 62% than ZK60 alloy. Although grain boundary is commonly considered as defect to deteriorate transport property, GNP(0.04)/ZK60 composite with largely refined grain size conducted superior thermal conductivity of 139.4 W.(mK)(-1) than ZK60 alloy (132.2 W.(mK)(-1)) at room temperature. The dispersed GNPs in matrix provide beneficial networks for efficient load and heat transfer. This work explores that graphene reinforcement is an effective way to simultaneously improve the mechanical and thermal properties of Mg alloys for enlarged applications.