Study On The Mechanical Properties Of Tensile And Indentation Of Graphene/Cu Nanocomposites

Recently,the applications of graphene have made amazing progress in many fields.The study of graphene/metal composites is one of the most important research directions of the applications of graphene.With the development of science and technology,the requirements for materials are developing towards the direction of light-weight,high-strength and multi-function,gradually.The traditional metal materials can't meet these needs,so the development of metal-matrix composites is imperious.For metal-matrix composites,graphene is undoubtedly a good reinforcement material.In this work,graphene/Cu composites are chosen as the research object,whose mechanical properties of tensile and nano-indentation are studied by MD method.The content of this study is mainly divided into two parts.Part one,the tensile numerical models of graphene/Cu composites are established.The properties,including elastic property,formation of dislocation and crack extension rule of graphene/Cu composites are studied by MD method,and then the influences of graphene layers,strain rate and crack on tensile properties of graphene/Cu composites are deeply discussed.Firstly,by analyzing the tensile results of Cu,SSG/Cu and DSG/Cu,it is found that the addition of graphene can improve the elastic modulus and ultimate strength of composites and the more content of graphene,the greater the elastic modulus and ultimate strength.Afterwards,by analyzing the tensile results of SSG/Cu under different of stain rate,it is found that the ultimate strength of SSG/Cu increases with the increasing of strain rate but the elastic modulus basically remains unchanged.Lastly,by analyzing the tensile results of SSG/Cu with different sizes of crack,it is found that the ultimate strength and elastic modulus of SSG/Cu decreases with theincreasing of crack size.Part two,the nano-indentation numerical models of graphene/Cu composites are established and the mechanical properties,including load-displacement curves,hardness,elastic modulus,formation of dislocation and plastic deformation,of nano-indentation for graphene/Cu composites are studied by MD method.Then the influence of graphene layers,position of graphene,maximum indentation depth and void on mechanical properties of nano-indentation for graphene/Cu composites are extensively discussed.Firstly,by analyzing the indentation results of Cu,SLG/Cu and DLG/Cu,it is found that the addition of graphene can improve the peak load,hardness and elastic modulus of composites,and the more content of graphene,the better the mechanical properties.Meanwhile,we find that the residual dislocation after unloading is the fundamental cause of plastic deformation.Secondly,the effect of the graphene position on mechanical properties of nano-indentation for SLG/Cu composite is discussed.It is found that the larger the distance of graphene from the indentation surface,the lower the peak load,hardness and elastic modulus,and the microscopic mechanism of the enhancement of graphene by inhibiting the slip extension of dislocations is explained.Afterwards,the effect of the maximum indentation depth on mechanical properties of nano-indentation for SLG/Cu composite is discussed.It is found that with the increasing of maximum indentation depth,the peak load,elastic modulus and residual plastic deformation increases gradually,but hardness decreases.Lastly,the effect of spherical void on mechanical properties of nano-indentation for SLG/Cu composite is discussed and it is found that with the increasing of the radius of spherical void,the peak load,hardness and elastic modulus decreases gradually.