Anisotropic Mechanical Properties of Graphene Nanosheet-Reinforced Powder Metallurgy Nickel-Based Superalloy

Herein, a graphene nanosheet (GNS)/nickel-based superalloy matrix composite with certain orientated GNS is fabricated via the powder metallurgy method. The solution mixing method is applied to obtain a superalloy powder with embedded GNS. Well-arranged GNS in the composite can be obtained by subsequent hot isostatic pressing, isothermal extrusion, and isothermal forging, which lead to anisotropic mechanical properties with ductility in radial and tangential direction better than in axial directions. Consequently, a moderate strength improvement (111-116 MPa at 0.1 wt% GNS) is achieved in the composite without losing its ductility in radial and tangential direction, while the elongation reduces from 21.0% to 15.7% in the axial direction. When the loads are perpendicular and parallel to the GNS alignment direction, respectively, two different interface failure modes of "GNS interlayer delamination" and "GNS pulled out" are caused, which result in the anisotropic mechanical behavior. This finding may provide a new perception in informing the strengthening behaviors of GNS-reinforced FGH96 composite.