Development of structure and properties in bimetallic Al/Cu sandwich composite during cumulative severe plastic deformation

Development of modern materials is non-negligibly connected with enhancement of their mechanical and utility properties, which can advantageously be performed via optimized deformation processing. The study presents preparation of Al/Cu sandwich composite, reinforced with Cu-wires, by the twist channel angular pressing (TCAP) method. Extrusion of the sandwich composite via single and double pass TCAP was simulated using the finite element method, and performed experimentally. The predicted deformation behaviour was verified by 3 D Micro-CT scanning, as well as detailed microstructure observations. The results showed that already the single TCAP resulted in substantial deformation strengthening of both the component metals, and the effective strain imposed within the Al-sheath reached the value of 5 after the second pass. The Al-sheath also featured homogeneous distribution of the lowest absolute values of residual stress, and the smallest average grain size of 1.66 mu m. The Cu grains within both the composites were also significantly refined, to almost 3 mu m after the second pass. Nevertheless, the observed parameters featured slight variations across the composites' cross-sections, which can be attributed to the plastic flow behaviour phenomena. The severe imposed shear strain also resulted in increase in microhardness and imparted changes in the thermal conductivity.