Abstract
Graphene is the strongest material ever tested and graphene nanoplatelets (GNPs) may be added to metal matrix to produce composites of better mechanical properties. In this chapter, the effect of GNPs' addition on the mechanical properties of pure Mg and its alloys (Mg-1Al, Mg-10Ti and Mg-1Al-1Sn) is reviewed. Mg-graphene composites were fabricated using semi-powder metallurgy method. The mechanical properties of composites were examined through tensile, compression and hardness tests. It was found that the effect of GNPs addition on tensile strength of pure Mg matrix is not so significant, something that may be attributed is poor wettability between matrix and GNPs. One the other hand, addition of GNPs into Mg alloys matric led to significant improvement in mechanical strength. The synergetic effect of graphene and carbon nanotubes was investigated in the Mg-1Al alloy matrix. Mechanical characterization revealed that composite reinforced with hybrid GNPs+CNTs particles exhibited higher tensile failure strain relative to those reinforced with individual GNPs and MW-CNTs. Addition of GNPs into Mg-10Ti alloy led to increase in tensile strength and ductility simultaneously. When the GNPs were added to Mg-1Al-1Sn alloy, tensile strength of the resulting composite was increased; however, ductility was adversely affected. The increased mechanical strength of GNPs reinforced magnesium composites corresponds to mismatch in coefficient of thermal expansion (between matrix and reinforcement particles), resulting in punching of dislocations at the interface, Orowan looping and load transfer from soft matrix to hard reinforcements or second phases.