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The evolution of constituent particles and the precipitation behavior in a commercial 2024 alloy during various homogenization regimes and their effect on T4-state mechanical performance have been investigated quantitatively. A typical phase transformation of AlCuFeMn → Al7Cu2Fe + Al20Cu2Mn3 gradually occurred during homogenization was identified as the duration time increasing, resulting in a "composite-particle" configuration with flocculent morphology. Meanwhile, nano-sized T-Al20Cu2Mn3 continuously precipitate within the matrix as the homogenization proceeding. The H1 treatment (445 °C/18 h + 495 °C/2 h) produced the higher number density of T phase with a finer size, while H2 regime (445 °C/18 h + 495 °C/6 h) caused a more complete precipitation and thus increased the fraction of S-texture component after subsequent rolling and T4-treatment. At T4 state, the superior mechanical properties of the H1 plate were obtained compared with the H2 sample, owing to the better dispersion-strengthening effect from T phase. In addition, the higher ductility can be attributed to the less weak-bonding interfaces and less recrystallization resistance from inadequate AlCuFeMn phase transition and T-precipitation, respectively. This work will provide useful insights to regulate the homogenization regimes for 2024 alloys in industrial applications.
Zhou et al. (Wed,) studied this question.