Simultaneous SAS and 100 Experiments on Phase Decomposition and Reversion in Al–Li Binary Alloys

Okuda, Hiroshi; Tanaka, Ichiro; Osamura, K.; Osawa, Makoto; Ito, Kazuhiro; Amemiya, Yoshiyuki

doi:10.1107/s0021889897002409

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…dissolution of subcritical d' precipitates formed directly after quenching or during the early DSC heating ramp [39][40][41]. However, its origin is controversially discussed, as the supersaturated solid solution (SSSS) of binary Al-Li alloys could pass different transformation pathways after quenching into the a þ d' two-phase field depending on the Li concentration [42,43]. Moreover, the early decomposition in quenched Al-Li alloys is too fast for direct experimental observations [42,[44][45][46] as clearly evidenced by the AQ DSC curve (Fig.…”

Section: Methodsmentioning

confidence: 99%

The Li stance on precipitation in Al–Li-based alloys: an investigation by X-ray Raman spectroscopy

et al. 2022

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Decomposition and precipitation processes in a binary Al–Li alloy and a technical Al–Li–Cu–Mg alloy were investigated using differential scanning calorimetry and X-ray Raman spectroscopy (XRS). The formation of $$\delta $$ δ ’ and T1 precipitates in the Al–Li and the T8 heat-treated Al–Li–Cu–Mg alloy, respectively, was confirmed using DSC. The XRS measurements complemented by simulated spectra allowed for probing specifically Li and its environment within the Al matrix. Based on linear combination fits of the XRS spectra, the relative contributions of $$\delta '$$ δ ′ and T1 precipitates were quantified. These results are in agreement with estimates of the relative amount of Li taking part in the precipitation process. Difficulties and limitations of the application of XRS to Al alloy systems are also discussed.

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Section: Methodsmentioning

confidence: 99%

The Li stance on precipitation in Al–Li-based alloys: an investigation by X-ray Raman spectroscopy

et al. 2022

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“…Taking experiences from previous works on the d 0 in high-Li Al-Li alloys, we know that its ordering transformation is through congruent ordering ? spinodal decomposition at * 140°C [24]. In consideration of the so strong temperature-dependent solubility and mobility of Li atoms in Al-Li alloys, it is difficult to have spinodal decompositions following congruent ordering to form the d 0 at high temperature.…”

Section: Aging Temperature-dependent Thickening Modelsmentioning

confidence: 99%

Uncovering the influence of Cu on the thickening and strength of the δ′/θ′/δ′ nano-composite precipitate in Al–Cu–Li alloys

Wang

Zhang

et al. 2021

J Mater Sci

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Nanoscale d 0 /h 0 /d 0 composite precipitate, as another important strengthening phase in the latest generation of Al-Li alloys, exhibits excellent resistance to coarsening. Here, we propose two thickening models for an anomalous d 0 /h 0 /d 0 that is discovered recently, by analyzing various influencing factors, including the static energy barrier, aging temperature-dependent nucleation conditions, and the elastic distortion suffered during growth. It indicates that the thickness of the d 0 /h 0 /d 0 composite precipitate seems to depend on the nucleation of the d 0. At elevated aging temperatures, h 0 precipitates can grow and thicken rapidly until the d 0 nucleates on them. This is strikingly different from the dislocationinduced growth mechanism. Subsequently, we propose a vacuum-added methodology to accurately extract the interfacial energy. The results show that this nano-composite precipitate can realize supra-nanostructure in thickness at low aging temperatures due to the spontaneous nucleation of the d 0 upon the pre-precipitate h 0. Cu atoms segregated at the interface suppress the nucleation of the d 0 , but release the lattice distortion to some extent. Using Griffith fracture model-assisted ab-initio uniaxial tensile tests, the cohesion strength and fracture process of this composite precipitate with and without Cu segregation have been captured. It indicates that the Cu atoms induced interfacial expansion and the fracture of strong Al-Al covalent bond, resulting in a reduction of fracture strength of this nano-composite precipitate.

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“… 11 employing Monte Carlo simulations could not find any evidence for congruent ordering in supersaturated fcc systems, questioning the validity of the mean-field BWG approach for modeling kinetics in general. Simultaneously, Small Angle X-ray Scattering experiments in combination with Wide Angle X-ray Scattering or calorimetric measurements performed on binary Al-Li alloys 1 , 2 , 12 suggested that both processes, ordering and decomposition, happen concurrently but with different velocities. Recently, Kobayashi et al .…”

Section: Introductionmentioning

confidence: 99%

L12 ordering and δ′ precipitation in Al-Cu-Li

Neibecker

Leitner

Kushaim

et al. 2017

Sci Rep

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The precipitation mechanism of the δ′ (Al3Li) phase in Al-Li alloys has been controversially discussed in recent decades, specifically with respect to a conjectured congruent ordering process. However, kinetics in the Al-Li system does not allow to resolve the intermediate stages of precipitation and hence to experimentally clarify this issue. In this paper, we are revisiting the subject in ternary Al-Cu-Li alloys with pronouncedly slower kinetics, employing Transmission Electron Microscopy, High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy, Differential Scanning Calorimetry and Atom Probe Tomography. The results show clear evidence for congruent ordering in a selected compositional range, revealing an already strongly L12 ordered microstructure after natural aging with a chemically homogeneous Li distribution and a decomposition of the alloy upon annealing at elevated temperatures. The presented study of the δ′ precipitation evaluates the reaction pathway of this process and compares it to the predictions of the Bragg-Williams-Gorsky model with respect to decomposition and ordering in this alloy system.

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Simultaneous SAS and 100 Experiments on Phase Decomposition and Reversion in Al–Li Binary Alloys

Cited by 7 publications

References 10 publications

The Li stance on precipitation in Al–Li-based alloys: an investigation by X-ray Raman spectroscopy

The Li stance on precipitation in Al–Li-based alloys: an investigation by X-ray Raman spectroscopy

Uncovering the influence of Cu on the thickening and strength of the δ′/θ′/δ′ nano-composite precipitate in Al–Cu–Li alloys

L12 ordering and δ′ precipitation in Al-Cu-Li

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