Atomic Scale Simulation Of Interfacial Properties Of Graphene/Aluminum Matrix Composites

Aluminum alloys are widely used due to the excellent properties.Graphene is an ideal reinforcement to improve the performance of metal materials.However,the research of graphene/Al composites still has many problems such as unclear interface bonding.The first-principles caculation can deeply study the interface electronic structure,atomic structure,interface bonding strength and stability of composite materials from the atomic and electronic scales through quantum mechanics methods,and make reasonable predictions on the interface properties and the overall properties of the materials,providing basis for interface design.In this paper,a series of composite material interface models such as Al/graphene oxide/Al interface,Al alloy/graphene/Al alloy interface and Al/doped graphene/Al interface are constructed.Their atomic structure,a series of properties such as interface bonding and interface electronic structure.The effects of functional groups,alloying element types and doping atom types on the properties of the Al/graphene/Al interface were analyzed and studied.Models of the Al/graphene oxide/Al interface with different functional groups were built,and the combination of epoxy,carbonyl and hydroxyl groups with the Al matrix and graphene in the Al/graphene/Al interface was analyzed.All three functional groups can stably exist on the interface.While interface forming,the existence of the functional group significantly reduces the Al/graphene/Al interface spacing and significantly improves the interface adhesion work.The three functional groups tend to be far away from the graphene and close to the Al layer.Epoxy O atoms and hydroxyl O atoms are basically separated from the graphene surface and enter the Al atomic layer.The O atoms in the hydroxyl groups can bond with Al atoms and H atoms,while there is still electron transfer between the carbonyl O atom and the graphene C atom,and it has not completely separated from the graphene layer.It shows that the existence of functional groups is conducive to interface bonding and enhances the strength of the interface.When there are oxygen-containing functional groups on the surface of graphene,Al atoms are easy to chemically bond with O atoms in it to form the interface product Al₂O₃,forming new interfaces.Al/Al₂O₃/Al interface and Al₂O₃/graphene/Al₂O₃interface are established to analyze the influence of interface oxide on interface properties.Through calculations,it is found that the adhesion of Al/Al₂O₃/Al interface is better than that of Al₂O₃/graphene/Al₂O₃ interface,and the adhesion work of Al₂O₃/graphene/Al₂O₃ interface is higher.Compared with the Al/graphene/Al interface,the adhesion work of the oxide-generated interface is increased.The presence of interfacial oxides enhances the interfacial bonding.Interface models with alloying elements are established to analyze the influence of common alloying elements in Al alloys on the interface.The adding of Mg can reduce the interfacial distance,improve the interfacial adhesion work,and form a metal compound with Al.The adding of Si expands the interfacial distance,reduces the interfacial adhesion work,and forms a bond with Al;the introduction of Cu reduces the interfacial distance and improves the interface adhesion work,and forms a good bond with Al.Therefore,the introduction of Mg and Cu elements in the interface is conducive to interface bonding and interface enhancement,while the introduction of Si is not conducive to interface bonding.In the Al/graphene/Al interface,when Si is used as the dopant atom of graphene,it can form a strong covalent bond with C atoms,reducing the interfacial distance,and improving the interface adhesion work.When P is used as the dopant atom of graphene,the interface forms an asymmetric structure,and the interface bonding is poor.When S is used as the dopant atom of graphene,it forms a good bond with C and the interface distance is reduced.Therefore,the introduction of Si and S into the interface as graphene dopant atoms or modified atoms is beneficial to the interface,while P as the dopant atom will destroy the original bonding of the interface,which is unfavorable for the interface bonding.