Microstructure Evolution and Cooperative Strengthening Mechanism of Copper–Aluminum Bimetal Continuous Equal Channel Angular Pressing-Annealing Process

This article investigates the atomic thermal diffusion process and microstructure evolution of copper–aluminum bimetallic structures under the route A continuous equal channel angular pressing technology combined with different long-term annealing processes. Scanning electron microscopy, x-ray diffraction, and electron back scattering diffraction were used to observe texture evolution, grain orientation, and atomic diffusion processes. The mechanical properties were characterized using a universal mechanical testing machine. The results show that after 4 passes of extrusion, the bimetallic crystallographic orientation is consistent (111), and the copper grains appear fibrous. An increase in annealing time induces a deepening of the atomic bonding layer, with the thickest reaching 30 μm. Transitioning from {112}<110>R-copper texture to {110}<001>R-Cube texture. Under the process of Route A 4 passes+1 h 450 °C, the mechanical property is significantly improved, with a strength of 270 MPa, a bonding strength of 70 MPa, and a conductivity of 94% International Annealed Copper Standard.