Atomic diffusion mediated by vacancy defects in pure and transition element (TM)-doped (TM = Ti, Y, Zr or Hf) L1 2 Al 3 Sc

Shi, Tao-Tao; Wang, Jia‐Ning; Wang, Yaping; Wang, Hai-Chen; Tang, Bi‐Yu

doi:10.1016/j.matdes.2016.07.008

Cited by 16 publications

(14 citation statements)

References 56 publications

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“…The favourable trend of V replacing Mo could potentially offer additional insight/data to the understanding of Mo-related carbides, which is difficult to be observed in full experimentally. This will help unlock some key links of knowledge in phase formation and transformation in advanced alloy design by combing the framework of first principles calculations (detailed data/trend analysis) and thermal dynamic simulations with controlled advanced experiments [39,40,49,53,[55][56][57][58][59][60].…”

Section: Discussionmentioning

confidence: 99%

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

et al. 2022

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In this paper, first principles method was adopted to investigate the point defects, Vanadium-related defects and defect combinations (vacancy (V), substitutional (S) and/or interstitial (I)) in molybdenum β-Mo2C and explore the use of first principles calculation data in analysing the link between different carbides and the effects of doping elements. Supercell models with different defect types were established and optimized, and the formation energy data of defects was developed. The structure evolution during the optimization process is analysed in detail to establish the main characteristics of changes and the relevant electronic properties. The data for different types of intrinsic defects and combined defects complexes was developed and key results is analysed. The results show that carbon vacancy (VC) is stable but does not inevitably exist in pure β-Mo2C. Interstitial site II is a very unstable position for any type of atoms (Mo, V and C), and analysis of the structure evolution shows that the atom always moves to the interface area near the interstitial site I between two layers. In particular, a C atom can expand the lattice structure when it exists between the layer interfaces. One type of the defects studied, the substitution of Mo with V (designated as ‘SV-Mo’), is the most stable defect among all single point defects. The data for defect complexes shows that the combination of multiple SV-Mo defects in the super cell being more stable than the combination of other defects (e.g., ‘VMo+IC’, ‘SV-Mo+VC’). The data with increasing SV-Mo in (Mo, V)2C system is developed, and typical data (e.g., formation energy) for Mo-rich carbides and V carbides are correlated and the potential of the data in analysing transition of different carbides is highlighted. The relevance of using first principles calculation data in the studying of V-doping and the complex carbides (V- and Mo-rich carbides) evolution in different materials systems and future focus of continuous work is also discussed.

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Section: Discussionmentioning

confidence: 99%

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

et al. 2022

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“…The mechanical properties and structural stability of Al 2 RE directly affect the strength of the whole Al-Mg-RE alloy [19,29,33,38,39]. The structure of Al 2 RE phase was drawn by the software VESTA [40] (see figure 2(a)), and the blue and magenta balls stand for the Al and RE atoms, respectively.…”

Section: Stability and Mechanical Propertymentioning

confidence: 99%

First-principles study of the mixing effects of rare earth solute atoms on the physical properties of Al₂RE phases in Al-based alloys at finite temperatures

et al. 2023

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The structural stability, mechanical properties, internal nucleation and growth mechanisms, and surface energies of Al2RE (RE=Sc, Y, La-Lu) second phases in Al alloys have been investigated by combining first-principles calculations with the Debye model. The results show that the lattice mismatch of Al2RE precipitates with Al matrix, which determines the strength of materials associated with dislocation slips, are closely related to the transferred electron et between Al and RE atoms. Furthermore, the methods of cluster expansion (CE) and special quasi-random structures (SQS) have been adopted to calculate the mixing enthalpy Hx of Al2RE11-xRE2x (RE1=La, Ce, Pr, Nd; RE2 is the rest RE atoms) for studying the possibility of replacing in the Al2RE (RE=La, Ce, Pr, Nd) compounds, which is explored in experiments, and it is found that the mixing enthalpy Hx increases with the substitute concentration. The calculated elastic constant Cij, bulk modulus B, shear modulus G, Young’s modulus E decrease with increasing atomic number from Sc to Y at first, and then increases to Lu; while the Cauchy pressure C12-C44 and pugh’s ratio B/G show the opposite trends. Moreover, the critical nucleation radius R* and coarsening rate KLSW of Al2RE are obtained from the classical nucleation theory (CNT) and LSW model, respectively. The results show that, the R* for all interfaces decreases from Y to La at first, and then increases linearly to Lu; whereas the KLSW of all models increases from Y to Ce firstly, and then changes very little. Finally, the calculated surface energy Esur of all Al2RE compounds is much higher than that of Al, and with the increase of atomic number, Esur of Al2RE intermetallic compounds decreases firstly from Sc to La, and then increases to Lu. The result is helpful for the further optimal designing high performance of Al alloys.

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“…First-principles calculations by Fan [ 21 , 22 ] showed that with the increase of the atomic number, the diffusion rate of rare-earth elements increased from Sc to Y, La, and then decreased to Lu. Shi et al [ 23 ] investigated the atomic diffusion of pure and transition-element (TM)-doped L1 2 -Al 3 Sc based on first principles and found that under a strong Al-rich condition, the V Sc defect obtained low formation energy and the NNJ mechanism mediated by V Al was most favorable for Sc atomic diffusion. TM dopants increased diffusion activation energy for dominant Al 3 Sc diffusion.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Study of Atomic Diffusion by Vacancy Defect of the L12-Al3M (M = Sc, Zr, Er, Y) Phase

Liu,

Liao,

Nie

et al. 2023

Molecules

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Atomic diffusion by the vacancy defect of L12-Al3M (M = Sc, Zr, Er, Y) was investigated based on a first-principles calculation. The point defect formation energies were firstly evaluated. Then, the migration energy for different diffusion paths was obtained by the climbing-image nudged elastic band (CI-NEB) method. The results showed that Al atomic and M atomic diffusions through nearest-neighbor jump (NNJ) mediated by Al vacancy (VAl) were, respectively, the preferred diffusion paths in Al3M phases under both Al-rich and M-rich conditions. The other mechanisms, such as six-jump cycle (6JC) and next-nearest-neighbor jump (NNNJ), were energetically inhibited. The order of activation barriers for NNJ(Al-VAl) was Al3Zr < Al3Y < Al3Er < Al3Sc. The Al3Sc phase had high stability with a high self-diffusion activation barrier, while the Al3Zr and Al3Y phases were relatively unstable with a low self-diffusion activation energy. Moreover, the atomic-diffusion behavior between the core and shell layers of L12-Al3M was also further investigated. Zr atoms were prone to diffusion into the Al3Y core layer, resulting in no stable core-shelled Al3(Y,Zr), which well agreed with experimental observation.

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Atomic diffusion mediated by vacancy defects in pure and transition element (TM)-doped (TM = Ti, Y, Zr or Hf) L1 2 Al 3 Sc

Cited by 16 publications

References 56 publications

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

First-principles study of the mixing effects of rare earth solute atoms on the physical properties of Al₂RE phases in Al-based alloys at finite temperatures

First-Principles Study of Atomic Diffusion by Vacancy Defect of the L12-Al3M (M = Sc, Zr, Er, Y) Phase

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Atomic diffusion mediated by vacancy defects in pure and transition element (TM)-doped (TM = Ti, Y, Zr or Hf) L1 2 Al 3 Sc

Cited by 16 publications

References 56 publications

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

Insight into Point Defects and Complex Defects in β-Mo2C and Carbide Evolution from First Principles

First-principles study of the mixing effects of rare earth solute atoms on the physical properties of Al2RE phases in Al-based alloys at finite temperatures

First-Principles Study of Atomic Diffusion by Vacancy Defect of the L12-Al3M (M = Sc, Zr, Er, Y) Phase

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First-principles study of the mixing effects of rare earth solute atoms on the physical properties of Al₂RE phases in Al-based alloys at finite temperatures