Hot deformation behavior and microstructural evolution of the Al-Cu-Li alloy: A study with processing map

The 2195 Al-Cu-Li alloy is widely utilized for the fabrication of key aerospace vehicle components; hence, an in-depth understanding of its hot deformation behavior is essential for consistently achieving high-per-formance products. In this study, isothermal compression tests were performed on 2195 Al-Cu-Li alloy ingots in the temperature and strain rate ranges of 250-500 degrees C and 10-3-1 s-1, respectively. A processing map was established to predict the workability under different conditions. The corresponding micro-structures were examined to reveal their hot deformation mechanism. Results demonstrated that the processing map was divided into four distinct domains. The unstable zone was located in the 250-375 degrees C/ 10-1.5-1 s-1 and 250-275 degrees C/10-2.5-10-1.5 s-1, temperature/strain rate regimes, in which deformation bands and flow localization were observed. The deformation bands blocked dislocations and compromised the dynamic recrystallization (DRX) behavior, hence damaging the microstructure. Further, large coarse T1 phases precipitated in the 325-410 degrees C/10-2.5-10-3 s-1 regime, which led to the formation of heterogeneities in the microstructure, corresponding to a minimum workability in the processing map. The optimal hot -working domain for the 2195 alloy was determined to be 460-500 degrees C/10-3-10-2 s-1, and the dominating hot deformation mechanisms were DRX and dynamic recovery (DRV). Specifically, continuous and dis-continuous DRX behaviors dominated in the 300-400 degrees C/10-3 s-1 and 450-500 degrees C/10-3 s-1 regimes, re-spectively. DRX gradually weakened as the strain rate increased at 500 degrees C. Further, the weakening of DRX was only minimally affected by temperature at 400-500 degrees C during high-speed deformation (1 s-1). The results reported herein can provide valuable insights into the hot working of Al-Cu-Li alloys. (c) 2022 Elsevier B.V. All rights reserved.