Molecular dynamics study of scratch behaviors in metallic glass/graphene composites: Role of graphene and probe

Metallic glasses (MGs) exhibit high strength, elasticity, and corrosion resistance; however, their limited ductility and poor wear resistance caused by the initiation and propagation of shear bands hinder their wider engineering applications. To address these issues, graphene layers are introduced as a reinforcing phase to form MG/graphene nanolaminate composites. Molecular dynamics simulations reveal that graphene layers effectively impede the propagation of shear bands and enhance the scratch properties by generating shear transformation zones that propagate laterally. When the graphene interlayer spacing is 1–1.5 nm, the load-bearing capacity is enhanced and the friction coefficient decreases. For MG/graphene/MG-1 with graphene interlayer spacing of 1 nm, the average friction coefficient is reduced to 0.67 compared with 1.69 for Cu₅₀Zr₅₀, corresponding to a 60 % decrease. At greater scratch depths, the reduction is even more pronounced, with the coefficient dropping to 0.49, nearly 71.7 % lower than that of the pure MG. Compared to the conical probe, the spherical probe increases the normal load by more than twice and decreases the friction coefficient by about 30 %, demonstrating a significant improvement in frictional performance. It reveals dual reinforcement mechanisms in MG/graphene composites—interlayer sliding and Shear Transformation Zone (STZ) regulation—and further demonstrates that graphene buffers the speed sensitivity of plastic deformation. These findings provide new atomistic insights beyond previous MD studies and establish a more comprehensive understanding of nanoscale tribological enhancement.