Investigation On The Structure And Properties Of Cu/Graphite-Zr Composite And Tic-Cu(Ag)(111)System

In this paper,the effects of Zr element content and graphite content on the interface modification and mechanical properties of copper/graphite composites were studied by experimental methods.The first-principles calculations have been used to study the stability and perperties of the surface and interface structure of Cu(111)/TiC(111)system and Ag(111)/TiC(111)system.The specific research is as follows:(1)The effects of active element Zr and Zr content on the interfacial modification of copper/graphite composites were investigated by vacuum hot pressing at 900 ?.XRD and SEM were used to study the phase composition and microstructure of the system with Zr content.The hardness test and compression performance of the samples were tested by using the Vickers hardness tester and the static hydraulic universal testing machine.The results show that the active element Zr reacts with graphite at the interface between copper matrix and graphite to form a new phase ZrC.The newly formed ZrC forms a uniform transition layer at the contact interface between copper matrix and graphite.The formation of the hard phase ZrC significantly increases the hardness and compressive strength of the copper/graphite composite.(2)The effect of graphite content change on mechanical properties of copper/graphite composites was studied by vacuum hot pressing at 900 ?.The results show that as the volume content of graphite increases,the hardness of the composite decreases gradually,and the compressive strength and ductility also decrease.This is because the copper as a supporting material in the copper-based composite material is gradually lowered,and excessive graphite seriously affects the performance of the copper/graphite composite material.(3)The first-principles calculations was used to study the surface properties,adhesion energy,interfacial energy,electronic differential density and density of states of Cu(111)/TiC(111)interfaces system.The results show that there are mainly ionic bonds at the C-terminal interfaces,and the stability of the Ti-terminal interfaces are determined by strong metal bonds.The Ti-HS-Cu interface has the largest adsorption energy(-2.904 J/m2)and the lowest interfacial energy(7.602-11.173 J/m2).The interaction between the Ti-HS-Cu interface is stronger and the interface structure is more stable.(4)The stability of the structure of Ag(111)/TiC(111)interface system,interface electrons,charge distribution and interaction were studied by first-principles method.The results show that the order of stacking sites at the Ti-terminal interface is HS>FS>AS,and the order of stacking sites at the C-terminal interface is FS>HS>AS.The results of charge density difference and density density analysis show that the Ti-terminal interface has weak metal bond bonding,while the C-terminal interface has ionic and covalent bonds,and the C-FS-Ag interface has more charge accumulation and stronger charge.