Homogenization of ECAPed Al 2024 alloy through age-hardening

Mechanical properties of aluminum alloys can be improved by obtaining ultra-fine grained structures via severe plastic deformation methods such as equal channel angular pressing (ECAP). In practice, however, the final structure may not be as homogeneous as desired. Thus, elimination of the inhomogeneity of ECAPed samples is a challenging task. In the case of age-hardenable alloys, a combination of ECAP and aging might provide new means of obtaining microstructural homogeneity. In this study, the effect of post-ECAP aging on the microstructural homogeneity of 2024 Al-Cu-Mg alloy was investigated. Following solutionization and rapid cooling, some samples were aged at 190 °C for various times. Another group of samples were similarly aged after one-pass ECAP through a 120° die. Throughout the aging of the samples, maps of microhardness variation were acquired in order to monitor the precipitation behavior. It was observed that considerable homogenization in the microstructure of the ECAPed samples was reached, especially right after peak aging. The homogenization level was characterized with the hardness inhomogeneity index. EBSD and TEM investigations were performed to observe variations in the homogeneity of the microstructure.