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The processability and final mechanical properties of Al-Li alloys are strongly affected by the uniformity of solute element and the degree of recrystallization, which can be improved via homogenization treatments. It is essential to control the microstructure to achieve the desired properties. In this work, the optimal double-step homogenization (DH) parameters for as-cast 2195 Al-Li alloy were first determined as 460 °C/16 h + 515 °C/20 h according to the comparative analysis, which fitted well with the results predicted by the corresponding kinetics modeling. Compared with the conventional single-step homogenization (SH), DH not only prevented the occurrence of overburning but also provided a more favorable condition for Al 3 Zr dispersoids to precipitate uniformly. The size and number density of Al 3 Zr dispersoids in the DH sample are finer and higher than those in the SH sample based on quantitative statistics. Due to the sufficient driving force for nucleation, the precipitate free zone (PFZ) of Al 3 Zr dispersoids was much narrower after DH. As a result, the DH sample possessed a higher Zener drag pressure, leading to a remarkable inhibition on the continuous evolution of substructures. Therefore, the recrystallization behavior in the DH sample was impeded effectively during the subsequent solution treatment. These findings are expected to provide reliable theoretical guidance for the industrial processing of as-cast 2195 Al-Li alloy. • Optimal double-step homogenization parameters were determined according to the microstructure and kinetics analysis. • Effect of homogenization on the precipitation and recrystallization behavior were quantified by HAADF-STEM and EBSD. • Fine, dense and well-distributed Al 3 Zr dispersoids with narrower PFZ were obtained via double-step homogenization. • The recrystallization resistance of 2195 Al-Li alloy can be effectively enhanced via double-step homogenization. [ABSTRACT FROM AUTHOR]

Dynamic precipitation and recrystallization behavior during middle-temperature and appropriate strain rates provide a chance to obtain desirable structure, which significantly improve the mechanical properties of aluminum alloys. In this paper, the microstructure evolution in the typical regions of processing map of 2195 Al-Cu-Li alloy during hot compression was observed via comparative characterization. The effects of dynamic precipitation and particle stimulated nucleation (PSN) on dynamic recrystallization have been analyzed systematically. At lower temperatures and higher strain rates, microshear band leads to a low power dissipation and provides preferential nucleation sites for T 1 precipitates. With temperature increases (<500 °C) and strain rate decreases, the T 1 precipitate bands are formed gradually due to the regular nucleation process on the microshear bands, which therefore limits the further growth of subgrains. Fine recrystallized grains along the grain boundary can also be obtained at high temperature via PSN stimulated by adequate stored energy, which was provided by large deformation near coarse secondary phases. Comprehensive continuous dynamic recrystallization (CDRX) is more prone to occur with the decrease of strain rate, leading to a higher power dissipation at 500 °C / 0.01 s−1. • The relationship between microstructure evolution and hot processing map of 2195 Al-Cu-Li alloy have been investigated. • The formation of T 1 precipitate bands was described, and its influence on dynamic recrystallization has been discussed. • The dynamic recrystallization behaviour around grain boundaries has been discussed. [ABSTRACT FROM AUTHOR]

The mechanical property anisotropy is one of the critical factors of limiting extensive application of the Al-Li alloy, which is mainly influenced by the textures, grain morphology and distribution of the aging precipitates. Through the plastic deformation process, the anisotropy can be weakened by regulating the grain structure. In this work, the final temperature-controlled rolling and cold rolling were carried out to investigate the grain structure variation and its effect on the mechanical property anisotropy of the spray-formed 2195 Al-Li alloy. The results show that the yield strength is improved but the anisotropy in the mechanical properties deteriorates as the final rolling temperature is elevated from 200 ℃ to 300 ℃. This is owed to the fibrous structures and a great number of deformation textures formed in the continuous static recrystallization process. Compared with the samples through final temperature-controlled rolling, the aged sample through cold rolling possesses higher yield strength and relatively weaker anisotropy due to the fine equiaxed grain structure. In addition, intense Brass and S textures existing in the plates are proven that can result in the heterogeneous distribution of the T 1 phase and the anisotropic equivalent slip system number values along the longitudinal and transverse directions, which both contribute to the strong anisotropy. To facilitate the analysis of the effect of the textures on the mechanical properties and anisotropy, the equivalent Schmid factor and slip system number were also calculated and discussed. This study looks forward to providing reliable theoretical support for the practical application of spray-formed Al-Li alloys. • The recrystallization behaviours have been discussed via different rolling schedules. • The equivalent Schmid factor was calculated and utilized to discuss the effect of texture on the yield strength. • The Schmid factor on different {111} planes was determined and explain the cause of the anisotropy in yield strength. • A novel calculation of ESSN was introduced to analysis the connection between the texture and elongation anisotropy. [ABSTRACT FROM AUTHOR]

• The influences of Cu content on microstructure evolutions and fatigue crack propagation behaviors of Al-Cu-Li alloys were firstly investigated. • The influences of secondary particle and recrystallized grain structure on the crack initiation has been discussed. • The relationship between crystal orientation and crack path deflection and its influences on the fatigue crack propagation has been discussed in detail. The fatigue crack propagation (FCP) behaviors of Al-Cu-Li cold-rolled sheets with different Cu contents were assessed systematically. The increase of Cu contents significantly reduces the threshold value of fatigue crack growth as secondary particles induce the initiation of microcracks, and provides more opportunities for crack deflection due to finer recrystallized grains. Moreover, Brass-orientated grains with low Schmid factor force the crack to change the direction of propagation, which prevents further crack propagation. Compared to Goss-orientated grains with small tilt and twist angle, cracks prone to deflect at its boundaries with large tilt angles difference between the adjacent grains. [ABSTRACT FROM AUTHOR]

• TTP and TTT diagrams of 2050 Al-Li alloy have been established. • The microstructure evolutions during interrupted quenching have been in-depth investigated. • The effects of microstructure evolution on tensile properties under different cooling rates has been investigated using cold-rolled thin sheets. The quench sensitivity of 2050 Al-Cu-Li alloy was determined by the time-temperature-transformation (TTT) curves and time-temperature-property (TTP) curves based on conductivity and hardness. Additionally, a novel end quenching test was used to investigate the quench sensitivity of cold-rolled sheets with a thickness of 2 mm which cannot be tested by conventional methods. The microstructure evolution during interrupted quenching (IQ) treatment and end quenching test was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The precipitation and coarsening of Cu-rich phases during quenching are the main factors affecting the quench sensitivity of the alloy. Meanwhile, these Cu-rich phases lead to the uneven distribution of precipitates (T 1 and θ′), which results in the decreased tensile properties. The influence of precipitate free zones (PFZs) on elongation during end quenching test was clarified and the high quench sensitive temperature zone was found to be 260 ~440 °C. This work can help to optimize the quenching process and improve the mechanical properties of the 2050 Al-Cu-Li alloy. [ABSTRACT FROM AUTHOR]