Mechanical Properties of Powder Metallurgy Nickel-Based Superalloy Composite Reinforced by Low Content Graphene Nanosheets

This study focuses on the effects of adding low content of graphene nanosheets (GNSs) (≤0.3 wt%) on microstructure and tensile property of GNSs-reinforced nickel-based superalloy (FGH96). The GNSs-reinforced FGH96 composite is fabricated by wet-chemical mixing and hot isostatic pressing. Microstructures and mechanical properties of the composites are studied by scanning electron microscope, transmission electron microscope, and static tensile tests. Results indicate that, when the addition amount of GNSs is less than 0.1 wt%, the tensile properties of the GNSs-reinforced FGH96 composites improve without losing their plasticity. The largest reduction of area (R/A) ratio of the composite is observed when 0.005 wt% GNSs is added, which is 81.4% higher than the unreinforced alloy. As the cross-sectional area of tensile sample reduces during necking, the GNSs/unit area increases, leading to the delayed fracture with an increase in R/A ratio and true fracture strength. Theoretical analysis suggests that the strengthening mechanism of GNSs–FGH96 belongs to the modified shear lag model. The interfacial shear stress caused by the presence of GNSs is the main reason for the increase in yield strength.