Identifying the crystal structure of T1 precipitates in Al-Li-Cu alloys by ab initio calculations and HAADF-STEM imaging

Wang, Shuo; Xiaonan, Yang; Wang, Junsheng; Zhang, Chi; Xue, Chengpeng

doi:10.1016/j.jmst.2022.05.056

Cited by 31 publications

(7 citation statements)

References 48 publications

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“…As is commonly reported, the T 1 phase is hexagonal with a space group of P6/mmm (lattice parameters of a = 0.496 nm and c = 0.935 nm) and a stoichiometry of Al 2 CuLi [13] . We show, however, a novel stable structure with the stoichiometry of Al 6 Cu 4 Li 3 by ab initio calculations and HAADF‐STEM imaging [10] . To control alloy microstructures and ultimately the mechanical properties, it is vital to understand the nucleation and growth of T 1 during precipitation.…”

Section: Introductionsupporting

confidence: 75%

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Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults

Wang,

Xue

et al. 2024

Materials Genome Engineering Advances

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Aluminum‐lithium (Al‐Li) alloy is one of the most promising lightweight structural materials in the aeronautic and aerospace industries. The key to achieving their excellent mechanical properties lies in tailoring T1 strengthening precipitates; however, the nucleation of such nanoparticles remains unknown. Combining atomic resolution HAADF‐STEM with first‐principles calculations based on the density functional theory (DFT), here, we report a counterintuitive nucleation mechanism of the T1 that evolves from an Eshelby inclusion with unstable stacking faults. This precursor is accelerated by Ag‐Mg clusters to reduce the barrier, forming the structural framework. In addition, these Ag‐Mg clusters trap the free Cu and Li to prepare the chemical compositions for T1. Our findings provide a new perspective on the phase transformations of complex precipitates through solute clusters in terms of geometric structure and chemical bonding functions.

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Section: Introductionsupporting

confidence: 75%

“…As one of the major strengthening mechanisms in Al‐Li alloys, precipitation strengthening is of great interests to many researchers [8–12] . Among them, the nano T 1 precipitate with high length/diameter ratios is the most important and has been well‐studied in the third and fourth‐generation Al‐Li alloys.…”

Section: Introductionmentioning

confidence: 99%

Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults

Wang,

Xue

et al. 2024

Materials Genome Engineering Advances

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“…It is clearly shown that our calculations using PBE have a better match with the results of previous experiments compared to those using LDA or PW91. Although the calculation overestimates (underestimates) the a 0 (B 0 ) of Al 3 Li by 0.4% (3%) and Al 3 Sc by 0.05% (3%), the accuracy is within the reliability range of computational models [76,[78][79][80]83,84].…”

Section: The Bulk Propertiesmentioning

confidence: 70%

“…models [76,[78][79][80]83,84]. Before we discuss the optimal doping position of Er in off-stoichiometric Al3X, it is necessary to have a good understanding of the nature of point defects in Al3X.…”

Section: The Bulk Propertiesmentioning

confidence: 99%

The Effect of Point Defects on Young’s Modulus of the Off-Stoichiometric Al3X (X = Li, Sc, and Zr) Phases: A First-Principles Study

Meng,

Wang,

et al. 2023

Metals

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L12-Al3X (X = Li, Sc, and Zr) precipitates are the main strengthened phases of high-strength aluminum alloys and are critical for aerospace structural materials. Point defects and substitutional ternary elements change the mechanical properties of Al3X. In this paper, the effect of point defects, including vacancy, antisite, and substitutional element addition defects on the elastic modulus of the off-stoichiometric Al3X (X = Li, Sc, and Zr) phase were investigated by using first-principle calculations. The formation enthalpies of the defective Al3X alloy and isolated point defects in Al3X were calculated, and the results showed that the defects have an effect on the structure and elasticity of the off-stoichiometric Al3X phases. The lattice distortion, elastic constants, and elastic moduli were further investigated. It was found that the point defects increased the Young’s modulus for Al3Zr, and the doping of Er improved the Young’s modulus for off-stoichiometric Al3Li and Al3Sc. Adjusting the position of vacancies can improve the elastic modulus. In addition, the doping of substitutional elements (especially Sc, Ti, Zr, Hf, Ta, Mn, Ir, and Cf) can greatly increase the Young’s modulus of off-stoichiometric Al3Li.

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“…Besides experimental studies on coatings and alloying to upgrade the corrosion resistance, theoretical studies of the corrosion behavior of Mg alloys are essential for more accurate and efficient design of corrosion resistant alloys [24,25] . Recently, Integrated Computational Materials Engineering has become a modern systems‐based approach for designing materials that meet specific performance by combining computational material models across multiple scales [26,27] . Many properties of alloys can be easily predicted using tools such as density functional theory (DFT) [28–30] .…”

Section: Introductionmentioning

confidence: 99%

First‐principle screening of corrosion resistant solutes (Al, Zn, Y, Ce, and Mn) in Mg alloys for Integrated Computational Materials Engineering guided stainless Mg design

Yang,

Wang,

Zhang

et al. 2024

Materials Genome Engineering Advances

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Mg alloy suffers from its poor corrosion resistance as a result of anodic dissolution of Mg and hydrogen evolution reaction (HER) in humid environments. In this study, the effects of alloying elements (Al, Zn, Y, Ce, and Mn) on both processes in Mg alloys have been quantitatively predicted. Using first‐principle calculations, we first obtained the substitution energies of alloying elements to compare their segregation preference, and then analyzed the influence of solutes at different layers on the stability and hydrogen adsorption properties of Mg(0001) surface by calculating the formation enthalpy, surface energy, vacancy formation energy, work function, Bader charge, deformation charge density, and adsorption free energy of H atom. It has been found that, on the one hand, the interior Mn solute atoms reduce the dissolution of Mg atoms and the transfer of electrons, consequently slowing down the anodic dissolution process. On another hand, the Mn, Y, and Ce elements on the surface inhibit the cathodic HER process by elevating the absolute value of hydrogen adsorption free energy, as a result of those solutes effectively controlling H adsorption behavior on Mg(0001) surface. In contrast, all five elements dissolved inside the Mg grain do not show significant effects on the H adsorption behavior.

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Identifying the crystal structure of T1 precipitates in Al-Li-Cu alloys by ab initio calculations and HAADF-STEM imaging

Cited by 31 publications

References 48 publications

Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults

Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults

The Effect of Point Defects on Young’s Modulus of the Off-Stoichiometric Al3X (X = Li, Sc, and Zr) Phases: A First-Principles Study

First‐principle screening of corrosion resistant solutes (Al, Zn, Y, Ce, and Mn) in Mg alloys for Integrated Computational Materials Engineering guided stainless Mg design

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Identifying the crystal structure of T1 precipitates in Al-Li-Cu alloys by ab initio calculations and HAADF-STEM imaging

Cited by 31 publications

References 48 publications

Unexpected nucleation mechanism of T1 precipitates by Eshelby inclusion with unstable stacking faults

Unexpected nucleation mechanism of T1 precipitates by Eshelby inclusion with unstable stacking faults

The Effect of Point Defects on Young’s Modulus of the Off-Stoichiometric Al3X (X = Li, Sc, and Zr) Phases: A First-Principles Study

First‐principle screening of corrosion resistant solutes (Al, Zn, Y, Ce, and Mn) in Mg alloys for Integrated Computational Materials Engineering guided stainless Mg design

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Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults

Unexpected nucleation mechanism of T₁ precipitates by Eshelby inclusion with unstable stacking faults