Interfacial structure evolution of the growing composite precipitates in Al-Cu-Li alloys

Duan, S.Y.; Wu, C.L.; Gao, Zi; Cha, Limei; Fan, Touwen; Chen, J.H.

doi:10.1016/j.actamat.2017.03.018

Cited by 81 publications

(14 citation statements)

References 51 publications

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“…Although θ precipitates in Al-Cu alloy have a large aspect ratio, this geometric feature may be changed by the addition of alloying elements which modify the interfacial energy between the Al matrix and the precipitate (Mitlin et al, 2000;Yang et al, 2016;Duan et al, 2017). Thus, it is interesting to analyze the influence of the precipitate aspect ratio on the mechanisms of dislocation-precipitate interaction in the presence of the SFTS.…”

Section: Influence Of the Aspect Ratio Of The Precipitatesmentioning

confidence: 99%

Discrete dislocation dynamics simulations of dislocation-θ′ precipitate interaction in Al-Cu alloys

Santos-Güemes

Esteban-Manzanares

Papadimitriou

et al. 2018

Journal of the Mechanics and Physics of Solids

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The mechanisms of dislocation/precipitate interaction were studied by means of discrete dislocation dynamics within a multiscale approach. Simulations were carried out using the discrete continuous method in combination with a fast Fourier transform solver to compute the mechanical fields (Bertin et al., 2015). The original simulation strategy was modified to include straight dislocation segments by means of the field dislocation mechanics method and was applied to simulate the interaction of an edge dislocation with a θ precipitate in an Al-Cu alloy. It was found that the elastic mismatch has a negligible influence on the dislocation/precipitate interaction in the Al-Cu system. Moreover, the influence of the precipitate aspect ratio and orientation was reasonably well captured by the simple Orowan model in the absence of the stress-free transformation strain. Nevertheless, the introduction of the stress-free transformation strain led to dramatic changes in the dislocation/precipitate interaction and in the critical resolved shear stress to overcome the precipitate, particularly in the case of precipitates with small aspect ratio. The new multiscale approach to study the dislocation/precipitate interactions opens the possibility to obtain quantitative estimations of the strengthening provided by precipitates in metallic alloys taking into account the microstructural details.

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Section: Influence Of the Aspect Ratio Of The Precipitatesmentioning

confidence: 99%

Discrete dislocation dynamics simulations of dislocation-θ′ precipitate interaction in Al-Cu alloys

Santos-Güemes

Esteban-Manzanares

Papadimitriou

et al. 2018

Journal of the Mechanics and Physics of Solids

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“…For instance, the addition of lithium to 0.5 wt.% facilitates the precipitation of θ′ (Al 2 Cu) phase with a refined dispersion in the matrix of 2xxx series aluminum alloys, while higher lithium content (1.0 wt.%) results in the formation of T 1 (Al 2 CuLi) as the dominant precipitant [23]. T 2 (Al 6 CuLi 3 ) [16] and δ′ (Al 3 Li) [24,25] phases are also common precipitates in Al–Cu–Li alloys. According to Li et al [16,26,27], the θ′ phase usually acts as the cathode compared to the matrix, while T 1 and T 2 are anodic to the alloy base, indicating that further addition of lithium can change the initiation behavior of pitting corrosion.…”

Section: Introductionmentioning

confidence: 99%

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part I: Effect of Li Addition by Microstructural, Electrochemical, In-situ, and Pit Depth Analysis

et al. 2019

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To analyze the effect of lithium and microstructure on the pitting corrosion behavior of aluminum alloys, three types of aluminum alloys were studied via scanning electron microscopy, transmission electron microscopy, electrochemical polarization, and by immersion tests coupled with in-situ observation of pitting and statistical analysis of pit depths measured by surface profilometry. It was found that, with increasing lithium content, the resistance to pitting corrosion was enhanced and the passive range was enlarged. In-situ observation revealed that the development of pitting corrosion exhibited three stages, including an initial slow nucleation stage (Stage I), a fast development stage (Stage II), and a stabilized growth stage (Stage III). Higher lithium content contributed to shorter time periods of Stages I and II, resulting in faster pitting evolution and a higher number of pits. However, the pits were generally shallower for the specimen with the highest lithium content, which is in agreement with the results of the electrochemical analysis.

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“…For this transformation, however, the h 0 thickening with modification of the d 0 to match the newly formed h 0 /d 0 interface structure will inevitably cause additional lattice distortions between the nanocomposite precipitate and the a-Al matrix, which in turn restricts the thickness of the h 0 precipitates. As a result, relatively thin d 0 /h 0 /d 0 precipitates (3-4 nm in total thickness with only 2-6 Cu-layers) were always observed in experiments [7,8,11].…”

Section: Introductionmentioning

confidence: 90%

“…In the past decades, the T 1 nano-precipitate as the most effective strengthening phase has attracted significant amounts of research efforts to favor its formation in Al-Li alloys through careful alloy design and thermomechanical processing [3][4][5]. Besides the T 1 , nanocomposite precipitates with the association of different precipitates, such as d 0 /h 0 /d 0 , h 0 /b 0 and h 0 /d 0 /b 0 , have been commonly found in Al-Li alloys by adding Cu and Zr elements [6][7][8]. It is proven that the preprecipitate h 0 can serve as a preferential site for the nucleation of d 0 and b 0 nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the d 0 /h 0 /d 0 nano-composite precipitate is attracting considerable attention in Al-Li alloys. Based on the analysis of atomic-resolution high-angle annular dark-field (HAADF) images in scanning transmission electron microscope (STEM) combined with density functional theory (DFT) calculations, its crystal structure, and the probable thickening mechanism have been proposed [7][8][9][10][11]. Interestingly, the thickening or coarsening of the h 0 phase sandwiched by d 0 phase on both sides is rather different from the conventional h 0 precipitate in Al-Cu alloys.…”

Section: Introductionmentioning

confidence: 99%

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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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Interfacial structure evolution of the growing composite precipitates in Al-Cu-Li alloys

Cited by 81 publications

References 51 publications

Discrete dislocation dynamics simulations of dislocation-θ′ precipitate interaction in Al-Cu alloys

Discrete dislocation dynamics simulations of dislocation-θ′ precipitate interaction in Al-Cu alloys

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part I: Effect of Li Addition by Microstructural, Electrochemical, In-situ, and Pit Depth Analysis

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

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