Study On Bimetallic Wire Of Copper Clad Aluminum And Copper Clad Steel By Clad-Drawing

The bimetallic wire is a new wire material with aggregative characteristic of double metals.The copper clad aluminum wire combines the beneficial properties of the wonderful conductivity of copper and the light-weight of aluminum.The copper clad steel wire combines the strength of steel with the conductivity and corrosion resistance of copper.Because of skin effect for alternating current,using the bimetallic wire as the inner conductor,coaxial cable has wonderful signal transmitting performance with light-weight or high strength,and often serves at a lower cost than copper wires. Especially,it is important meaning for incremental need of copper in industrial development.The clad drawing method has been widely used for the production of the bimetallic wire.But the investigation on the bonding mechanism of the bimetallic wire by clad drawing method and microstructure and properties of cladding wire is very deficiency,so it is disadvantageous for quality control and technology development. Therefore,with the development of bonding mechanism,microstructure and properties, it is theoretical and practical significance for researching advanced techniques and bimetallic wire application.The balance distance and binding energy of double atoms cluster that is made up of Cu-Al,Cu-Fe and Cu-Cu have calculated by quantum chemistry ab initio calculation method.A fit principle was put forward that the lowest point of the fitted curve of the potential energy should coincide with the minimal value calculated by quantum chemistry calculation,and the interatomic potentials of Cu-Al,Cu-Fe and Cu-Cu were obtained.The bimetallic bonding by clad drawing method is the action results of collective gravitation of a great lot of two metal surface atoms reciprocally by outside force that operate two metal bodies.The interatomic potential energy of the closer atoms of two metal surfaces is obvious lower so as to change for electron within the distance. The great area of two metal surfaces closes up by outside force depend on plastic deformation which is detached before solid bonding of Cu-Al or Cu-Fe bimetallic surface,and they overcome the action of excluding force of the interatomic potential energy in two metal surface.The heat activation due to the friction of two metal surfaces each other by plastic deformation activates surface atoms.The oxide layer on metal surface baffles bimetallic solid bonding,thereby it is the key of bimetallic bonding realization to wipe off oxide and to protect new surface.The static deformation of the convexity of contract surface layer is increasement at first moment of the plastic deformation by drawing process.At the same time,the rudimental oxide layer or thin oxide layer are crushed and new clean surfaces are provided,and that the opposite remove within contact surfaces is reduced since the friction force within two metal contact surface.After clad drawing,the atom diffusion of bimetallic interface happen in definite condition,and it is advantageous for increasing joint intensity,but it is not essential condition.On the based of the calculation of phase diagram of Cu-Al and Cu-Fe binary system,the solid solubility and diffusion coefficient of bimetallic conjoint layer were calculated.The diffusion coefficient increases when deformation increases on account of deformation storage energy.The intermetallic compound in interface layer of copper clad aluminum wire annealed.It is both benefit for continuative drawing and infaust for mechanics property and electrical conductibility.The atom diffusion of interface layer of copper clad steel wire annealed is carried out in single phase,thus it is advantageous for increasing joint intensity.The microstructure of copper clad aluminum and copper clad steel wires by drawing at room temperature is vimineous grain as fibril shape from prime equiaxed grain.The grain of longitudinal section is fibril shape,and the grain of transvers section is anomalistic shape.The fibril diameter is in inverse proportion to deformation and the fibril length is in direct proportion to square of deformation approximately.Beside, there is local boundary amalgamation discovered when great deformation by multi-drawing.The reversion and recrystallization from vimineous grain take place gradually when copper clad aluminum wire annealed at 350℃and copper clad steel wire armealed at 650℃after drawing at room temperature,and the vimineous grain transforms gradually to equiaxed grain.Merely,the frequency ofα-Fe grain size in copper clad steel wires annealed is disperse than the common.The ultimate tensile strength of copper clad aluminum and copper clad steel wires by drawing at room temperature increases in direct proportion to square root of deformation, and the elongation decreases and fluctuates.Basis of the ultimate tensile strength of prime pure copper and aluminum alloy or steel,the ultimate tensile strength of the cladding wires in different diameters can be doped out by mixed principle of composite material.The ultimate tensile strength of copper clad steel wire annealed at 650℃is closed to prime ultimate tensile strength,and the elongation of that is closed to prime elongation too.The resistivity of copper clad aluminum and copper clad steel wires by drawing at room temperature increases in direct proportion to deformation because the increment of the area of grain boundary results in increment of static disfigurement to electron dispersion,and the relative value of the resistivity increment is very small. Consequently,the cladding wire is provided with excellent conductivity.Basis of the resistivity of prime pure copper and aluminum alloy or steel,the resistance and resistivity of the cladding wires in different diameters can be doped out by parallel connection circuitry of copper layer and core wire.Otherwise,the equiresistance diameters for pure copper and copper clad aluminum wire can be doped out according to above method.When effect of deformation on resistivity of copper clad steel wire annealed is eliminated,the resistivity also reduces as normal instance.