Microscopic Strengthening Mechanism And Shear Mechanical Properties Between Interfaces Of Aluminum Based Graphene Composite Materials

Aluminum and its alloys have excellent properties such as lightweight,high thermal conductivity,high conductivity,and high corrosion resistance,making them one of the most widely used metal materials.However,due to the low strength of aluminum,it is gradually difficult for aluminum and its alloys to meet the increasing demand for metal service life and mechanical properties with the development of modern technology.By adding graphene reinforcement phase materials to the aluminum matrix,the strength of aluminum and its alloys can be greatly improved,making up for their insufficient strength and improving their comprehensive performance.This has made aluminum matrix composites,especially high toughness and high-strength aluminum based graphene composites,a research hotspot in recent years.Molecular dynamics simulation can be used to study the micro strengthening mechanism of aluminum based graphene composites from a micro perspective,which has important guiding significance for the preparation and design of aluminum based graphene composites.This article mainly uses molecular dynamics simulation calculations to study the microscopic mechanism of the interaction between a single dislocation and the aluminum graphene interface in shear driven aluminum based graphene composites from a microscopic perspective;The shear failure process,shear mechanical properties,and strengthening mechanisms at various stages of aluminum based graphene composite materials were studied:(1)A model of aluminum based graphene composite material containing a single dislocation was established,and the detailed process of shear stress driving a single dislocation to slip to the interface between aluminum(111)closely packed surface and graphene was studied,as well as the micro deformation mechanism of a single dislocation at the aluminum graphene interface.It was found that the slip of dislocations into the aluminum graphene interface formed a plastic/elastic interface at the interface,resulting in geometrically necessary dislocations and a back stress strengthening effect.Dislocations in the aluminum matrix entering the interface will cause the buckling deformation of graphene.Due to the high toughness of graphene,the buckling deformation of graphene will diffuse and buffer along the interface,repairing the lattice distortion of the aluminum matrix.A study was conducted on the buckling deformation of intact and defective graphene under the action of a single dislocation,and it was found that the severity of interfacial buckling deformation of graphene is directly proportional to the contact area between surface defects and dislocations.(2)A laminated aluminum based graphene composite material was established and its shear mechanical properties were systematically studied.It was found that the shear modulus of the composite material is 36.5 GPa,which is higher than 58.36 GPa of pure aluminum,and the overall strength and mechanical properties are also much higher than pure aluminum.The strengthening mechanisms of aluminum based graphene composite materials at various stages during the shear process were analyzed.It was found that the main strengthening mechanisms of the material during the shear elastic stage were load transfer and constraint effects.There were also back stress strengthening and dislocation strengthening mechanisms caused by dislocation entanglement during the yield and failure stages.The effects of the thickness of aluminum crystal layer and the area of graphene void defect on the shear mechanical properties and strengthening mechanism of aluminum based graphene composites were studied by the Control variates.It was found that the thickness of the aluminum substrate layer and the surface defect area of graphene can change the efficiency of load transfer and back stress strengthening between interfaces,resulting in an increase in the strength of the model as the thickness of the aluminum layer and the defect area of graphene decrease.The buckling fluctuation of graphene containing defects in composite materials is more severe,and the peaks and valleys are concentrated near the defects,making it more prone to fracture and failure,thereby reducing the confinement effect of aluminum matrix on graphene.