Abstract The effect of temperature was investigated on the consolidation of blended elemental powders of aluminum and copper by equal channel angular pressing (ECAP). Aluminum and Copper powders (1:1% vol.) were blended and consolidated in a 90° ECAP die at room (RT) and cryogenic temperatures (CT - ~77 K). ECAP samples were pressed until 4 passes at room temperature in route Bc. As a reference, a sample was obtained by conventional uniaxial pressing. The obtained results indicated a much denser (>99.5%) and harder structure by cryogenic ECAP. The hardness after one pass at CT was comparable with 4 passes at room temperature. Tensile tests performed at CT for materials with similar chemical composition showed a simultaneous increase in strength and ductility at CT, corroborating the results obtained by ECAP. The partial suppression of dynamic recovery and the activation and the transition between deformation mechanisms at CT, as well as stacking fault energies (SFE) of such metals, played an important role in these results. Copper presented a much higher capability of strain hardening than aluminum, due to its lower SFE and much lower homologous temperature. X-ray diffraction indicated a strong correlation between the variation of average microstrain and the variation of hardness on both metals. The results of this study demonstrated the great potential of the application of very low temperatures for the obtaining of deformation metal-metal composites.

Aluminum, copper and silver samples, all of them face-centered cubic (FCC) metals, were rolled at room and cryogenic temperatures until equivalent strains (ε) were between 3.23 and 4.13. The cryogenic temperature (CT) and room temperature (RT) rolled samples were evaluated by hardness tests and X-ray diffraction (XRD), which indicate influence of stacking fault energy (SFE) on process. Lower SFE metals tend to exhibit dislocation densities significantly increased and as consequence, hardness too. It was also noted that after sometime exposed to RT, the materials rolled at CT present hardness decrease.