Nanolaminate of metallic glass and graphene with high strength and elastic limit

Abstract

Metallic glasses have been suggested as promising materials in various technical applications such as biological sensors, actuators, and device coatings, due to their combined high electricity, corrosion resistance, and high elastic limit. Despite of superior characteristics, metallic glass is not widely used in applications due to catastrophic failure after elastic deformation. Many researchers have investigated to improve their limited plasticity. One way of suppressing shear failure is reducing metallic glass dimensions under 100 nm, thereby homogenous deformation occurs, leading to enhanced tensile strength and ductility. Another approach is introduction of an additional crystalline or amorphous phases into a metallic glass matrix. The crystal or amorphous phase is assumed to act as obstacle for shear band propagation and catastrophic failure. To investigate both approaches, we have developed metallic glass-graphene nanolaminate structures that utilize advantages of graphene, including 2-dimensionality, high modulus, and high strength, as ductility enhancer. Nanolaminate samples are fabricated with alternating layers of metallic glass and graphene. Metallic glass is deposited on a Si substrate using RF magnetron co-sputtering and CVD-graphene, synthesized on copper foil, is transferred on this metallic glass layer. Dog-bone-shaped samples for tensile testing are fabricated by undercutting the Si substrate and FIB patterning, and mechanical properties are measured by in-situ tensile testing. We discuss deformation behaviors of nanolaminates during tensile loading are dependent on the thickness of the metallic glass layer.