Study On The Texture Evolution Of Cu-Nb Composites And Mechanical Properties And Textures After Repeated Rolling And Annealing

Cu-Nb composite wire is a conductor material with high strength and high conductivity commonly used in pulsed high magnetic field.Through the systematic study of Cu-Nb composites with strong magnetic field,it can provide theoretical basis for material research,performance optimization and engineering application.In this paper,the mechanical properties and microstructure of Cu-Nb composites during repeated rolling annealing were studied by hardness test,room temperature tensile test,XRD diffraction analysis and scanning electron microscope.At the same time,the microstructure and Cu matrix texture of Cu-Nb composite wires with different drawing passes were characterized.The results are as follows:(1)In the process of extreme plastic deformation,Cu and Nb in Cu-Nb composites belong to FCC and BCC structures,and the crystal structure does not match.In the process of cluster drawing,when the strain is large enough,the Nb fiber will stretch and form strong deformation texture orientation.With the increase of the pullout path,the strain of Cu-Nb composite increases continuously.After four channels,the number of Nb core wires inside the wire is 854,the corresponding variable reaches 24.8,and the scale reaches the nanometer level.(2)The size of the matrix Cu varies gradually with the process,and the thickness of the Cu increases from the most inner layer to the most outer layer.The scale from the nanoscale to the micron shows a multiscale phenomenon.From the whole cross section,the Cu matrix is evenly distributed.With the increase of the pullout path,the Nb fiber in the cross section has a curl elongation or contraction,which leads to the presence of vacancy.In order to coordinate the deformation of the matrix Cu and the reinforcement Nb,the Cu can be supplemented in the place of the Nb vacancy,so the contact area of the matrix Cu and the reinforcement Nb increases,the density of the interface is increased,and the strength of the material is increased.(3)Two kinds of texture are found in the Cu matrix by the Cu-Nb composite prepared by the ADB,one is the <111> texture parallel to the drawing direction and the other is the <100> texture.With the increase of drawing passes,the texture types did not change,but the strength changed.As the strain increases,the texture of <111> increases first and then weakens.The change of <100> texture is opposite to that of <111> texture.The lattice constant of Cu matrix has no obvious change trend during the whole process,and the lattice constant of Nb decreases continuously.This is because with the increase of the pullout path,the strain of the material increases,the lattice distortion becomes larger,the residual strain becomes larger and the grain size decreases gradually.(4)During the process of repeated rolling and annealing,the mechanical properties of Cu-Nb composite material,such as hardness,tensile strength and modulus of elasticity,show a periodic variation law,which is different from the general material,showing the law of annealing hardening and processing softening.(5)In the process of repeated rolling annealing,the matrix Cu and reinforcement Nb at nanometer level play a leading role in the change of material properties.Annealing can reduce the dislocation growth and reaction in the crystal,so the strength of the material increases.Rolling deformation makes dislocation structure recover and promotes the yield process.Therefore,the strength of the material decreases and the ductility increases.(6)The tensile fracture morphology of the Cu-Nb composites after repeated rolling is more complex,and a large number of dimples appear in the middle area,but the fracture edge region remains a cleavage fracture,which is due to the multiscale effect of the Cu matrix.During the repeated rolling and annealing process,the number and density of dimples changed,and the toughness of the corresponding materials changed accordingly.