Structure And Properties Of In-situ Graphene Reinforced Nickel-Aluminum Matrix Composites

In-situ grown graphene reinforced Ni-Al matrix composites were fabricated by powder metallurgy and chemical vapor deposition.The morphologies and microstructures of the composites were characterized by SEM,XRD,Raman spectroscopy and TEM,and study the mechanical properties and tribological properties of composite materials.The main conclusion are as follows:?1?Graphene in the in-situ prepared composite material has uniform distribution in the Ni matrix,fewer defects,and good crystallinity.The solid solution of Al leads to the grain refinement of nickel in the composite.With the increase of Al content,the grain size of nickel decreases from 652.9 nm to 99.8 nm.At the same time,the solid solution of aluminum causes the Ni?111?diffraction peak to move from 44.6°to 44.3°,indicating that the solid solution of aluminum causes the Ni lattice to expand.The solid solution of Al in nickel plays an important role in the regulation of graphene structure.With the increase of aluminum content,the in-situ grown graphene defects become more and the number of layers decreases.?2?The mechanical properties of the composites were tested using a Vickers hardness tester and a computer controlled electronic universal testing machine.The results show that with the increase of Al content in the matrix from 0 at.%to 16 at.%,the composite hardness increases from 108.2 HV to 172.5 HV,and the yield strength significantly increases from 236 MPa to 411 MPa.The increase in strength is mainly due to solid solution,grain refinement,and second phase strengthening of graphene.In situ growth of graphene not only improves the strength of the Ni-Al matrix,but also exhibits an excellent toughening mechanism.?3?The tribological properties of the material were characterized by UMT-2 multi-functional friction and wear tester.The results show that with the increase of Al content,the friction coefficient of the composite decreases from 0.75 to 0.55,and the wear rate decreases from 3.97×10^-4 mm³/Nm to 2.43×10^-4 mm³/Nm.When the aluminum content is low,the plastic wear surface of the composite material undergoes plastic deformation and there is a large number of craters;when the Al content is high,the wear surface exhibits microcracks caused by fatigue wear,and spalling and furrows appear,manifesting as peeling wear and Abrasive wear.