Evolution of dislocation behavior and dynamic recrystallization in Al–Cu–Mg–Er alloy under coupled temperature-strain rate conditions: multiscale characterization and analysis of high-temperature formability
摘要
To reveal the microstructural evolution laws of the Al-5.0Cu-0.8Mg-0.5Mn-0.2Er alloy during high-temperature deformation under the coupling effect of temperature and strain rate, a systematic investigation was conducted on the flow behavior, grain boundary evolution, dislocation storage, and texture evolution of the alloy at 300–500 ℃ and 0.001–1 s−1 using hot compression tests combined with EBSD and TEM. The results show that with increasing temperature and decreasing strain rate, the flow stress decreases and the high-temperature softening effect is enhanced. Compared with the condition of 300 ℃/1 s−1, the volume fraction of dynamic recrystallization, the proportion of high-angle grain boundaries (HAGBs), and the geometrically necessary dislocation (GND) density at 500 ℃/0.001 s−1 increase from 1.8% ± 0.6% to 22.8% ± 3.2%, from 27.9% ± 1.5% to 39.8% ± 3.5%, and decrease from 6.69 × 1014 m−2 to 0.95 × 1014 m−2, respectively. Meanwhile, the texture evolution exhibits obvious sensitivity to strain rate: the ODF peak increases from 7.53 to 40.18 at 0.01 s−1, while it shows a trend of 10.00 → 18.32 → 12.90 at 0.1 s−1. The matching degree between temperature and strain rate significantly affects the dynamic recrystallization process, dislocation density evolution, and grain orientation distribution. Based on a comprehensive analysis, 500 ℃/0.001 s−1 is determined as a suitable parameter combination for high-temperature forming of this alloy.