Texture evolution and its influence mechanism on properties of single crystal copper and polycrystalline copper during cumulative deformation

Abstract

The φ16 mm single crystal copper rod was prepared by heated-mold horizontal continuous casting, and the φ16 mm polycrystalline copper rod was prepared by up-casting technology. Both of them were drawn to φ0.2 mm, the conductivity, strength, elongation, and microstructure evolution of single-crystal copper wire and polycrystal copper wire were compared and analyzed. The results show that the plasticity of as-cast single-crystal copper rod is 13.94% higher than that of as-cast polycrystalline copper rod. When drawing to φ0.2 mm, a single crystal copper wire with high strength (506 MPa) and high conductivity (98.01% IACS). At the same deformation amount, the single crystal copper wire obviously deforms more slowly and has a higher plastic deformation capacity; the texture transformation of single crystal copper wire is from soft → hard orientation, selective orientation to discrete distribution, while the weave transformation of polycrystalline copper wire is from soft → hard orientation, then from hard → soft orientation, and finally stabilizes to selective orientation. The microstructural evolution of single-crystal copper wire and polycrystalline copper wire during continuous deformation was observed: dislocation entanglement into dislocation cells by slip → microstrip structure → lamellar organization → twinning organization, single-crystal copper wire appears twinning later, single-crystal copper deformation coordination ability is better than polycrystalline copper. It is found that the increase of dislocation density, the decrease of grain width and the increase of texture are the main factors for the strength improvement of micro-nano pure copper wires.

Keywords

• Single crystal copper
• Polycrystalline copper
• Texture
• Large plastic deformation
• Strength
• Microstructure