Fabrication And Mechanical And Electrical Properties Of Bulk Cu-Based Laminated Composites Materials

Copper based materials with excellent mechanical and physical properties are widely used in aerospace,machining,power,electronics and other industries.However,the inverted relationship between the strength and conductivity and the strength and plasticity of conductive copper materials often exists,which limits the practical application of copper based conductor materials.The layered structure is considered to be an effective way to improve the inverse relationship between mechanical and electrical properties of copper for conducting.In this study,Cu/Ag and Cu/Cu-Cr-Zr layered copper matrix composites with excellent mechanical and electrical properties were successfully prepared by cumulative rolling and intermediate annealing.The microstructure evolution and mechanism of the layered structures during the cumulative rolling process were studied,and the mechanical and electrical properties and related mechanisms of the two layered materials were systematically studied.Bulk Cu/Ag composites with continuous layered structure,uniform and controllable layer thickness and clear interface were successfully prepared by the combination of CARB and intermediate annealing.The mechanical and electrical properties of the nanoscale layered Cu/Ag composite block show that it has high strength,high thermal stability and high electrical conductivity.In terms of mechanical properties,the tensile strength of 20 nm layered Cu/Ag composite is up to 938.1 MPa,and the fracture elongation is 7%,but the uniform elongation is less than 2%.Cu/Ag interface strengthening is the main strengthening mechanism.In terms of thermal stability,the material exhibits high temperature softening resistance of 500 °C,thanks to the dense thermodynamically stable Cu/Ag phase interface inside the material.When the service temperature exceeds 500 °C,the macroscopic mechanical properties and microstructure of the materials will appear obvious instability phenomenon,the main thermal instability mechanisms are grain boundary notch mechanism and Rayleigh instability mechanism,and Rayleigh instability mechanism is the dominant.In terms of electrical properties,the conductivity of the material under cold deformation is affected by the interface between dislocation and Cu/Ag phase,but it is still higher than 93% IACS,and reaches 100.5% IACS after annealing at 500 °C,showing excellent electrical conductivity.Although the layered Cu/Ag composite has excellent strength-conductivity matching relation,there still exists serious inverting relation of strength-plasticity contradiction.In order to improve the strength-plasticity inversion relationship in copper-based conductor materials.The coarse-fine grain heterogeneous layered Cu/Cu-Cr-Zr composite block was prepared by accumulative rolling welding(ARB)and appropriate heat treatment process,which consisted of alternating coarsegrained Cu layer and fine-grained Cu-Cr-Zr layer.The mechanical properties of Cu/Cu-Cr-Zr composites annealed at 400 °C /90 min with coarse-fine grain heterogeneous lamellar structure show that the composites can achieve the best strength-plasticity matching,with tensile strength of up to547 MPa and uniform elongation of 14.5%.The strength-plasticity contradiction of copper-based conductor material is improved effectively.The study on the strengthening and toughening mechanism shows that the mechanical properties of the material are affected by the heterogeneous structure,and the additional back stress is strengthened in the soft coarse-grained Cu layer,which improves the strain hardening ability of the material,thus making the material exhibit excellent strength-plasticity matching.The thermal stability of the material depends entirely on the Cu-Cr-Zr alloy layer,and its high temperature anti-softening temperature can reach 400 °C.The electrical properties show that the electrical conductivity of the material increases with the increase of heat treatment temperature or time,and the material exhibits excellent electrical conductivity of more than 90% IACS after annealing at 400 °C /90 min,and conforms to the volumetric mixing rule.