295 results on '"Zi-Kui Liu"'
Search Results
2. Understanding formation mechanisms of intermetallic compounds in dissimilar Al/steel joint processed by resistance spot welding
- Author
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Bo Pan, Hui Sun, Shun-Li Shang, Mihaela Banu, Pei-Chung Wang, Blair E. Carlson, Zi-Kui Liu, and Jingjing Li
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Strategy and Management ,Management Science and Operations Research ,Industrial and Manufacturing Engineering - Published
- 2022
3. Thermodynamic Modeling of the Nb-Ni System with Uncertainty Quantification Using PyCalphad and ESPEI
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Hui Sun, Shun-Li Shang, Rushi Gong, Brandon J. Bocklund, Allison Beese, and Zi-Kui Liu
- Published
- 2023
4. Phase Transformation and Equation of State in Ti-45al Alloy Under High Pressure
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Xi Li, Ruixiang Zhu, Jinghua Xin, Minsi Luo, Shun-Li Shang, Zi-Kui Liu, Chongshan Yin, Ken-Ichi Funakoshi, Rian Johannes Dippenaar, Yuji Higo, Ayumi Shiro, Mark Reid, Takahisa Shobu, Koichi Akita, Wei-Bing Zhang, and Klaus-Dieter Liss
- Published
- 2023
5. Corrosion behavior in aluminum/galvanized steel resistance spot welds and self-piercing riveting joints in salt spray environment
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Blair E. Carlson, Bo Pan, Zhuoyuan Zheng, Joseph C. Simmer, Shun Li Shang, Jingjing Li, Weiling Wen, Nannan Chen, Zi Kui Liu, Mihaela Banu, Pingfeng Wang, and Hui Sun
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Materials science ,Strategy and Management ,Alloy ,Metallurgy ,chemistry.chemical_element ,Pourbaix diagram ,Management Science and Operations Research ,engineering.material ,Chemical reaction ,Industrial and Manufacturing Engineering ,Galvanization ,Corrosion ,Galvanic corrosion ,symbols.namesake ,chemistry ,Aluminium ,engineering ,symbols ,Spot welding - Abstract
This paper underlined the corrosion behavior of aluminum alloy/galvanized steel joints fabricated by resistance spot welding (RSW) and self-piercing riveting (SPR) exposed to different salt-spray cycles. It was found that the crevice generated by different joining methods has an important impact on corrosion behavior. Compared with the RSW joint, less corrosion happened on the coupled regions in SPR joints because of the higher local pH value resulted from the smaller crevice. The crevice, however, has less impact on the types of corrosion products. Galvanic corrosion happened in the coupled region for both RSW and SPR joints. The Pourbaix diagram explained the stable corrosion products of Al and Zn Fe alloy, which are Al2O3, ZnO, and Fe3O4. Additional corrosion products observed from the experiment included α-Al(OH)3, Ca4Al2(CO3)(OH)12(H2O)5, Zn5(OH)8Cl2(H2O), Zn5(CO3)2(OH)6, and Fe2(OH)2(CO3), which can be understood by considering the metastable corrosion products, Pourbaix diagram, and possible chemical reactions.
- Published
- 2021
6. Machine learning-enabled identification of micromechanical stress and strain hotspots predicted via dislocation density-based crystal plasticity simulations
- Author
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Adnan Eghtesad, Qixiang Luo, Shun-Li Shang, Ricardo A. Lebensohn, Marko Knezevic, Zi-Kui Liu, and Allison M. Beese
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Published
- 2023
7. Electrochemical properties of Gd(III) ions in LiCl-KCl-GdCl3 at 723–1023 K
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Stephanie Castro Baldivieso, Nathan D. Smith, Zi-Kui Liu, and Hojong Kim
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General Chemical Engineering ,Electrochemistry ,Analytical Chemistry - Published
- 2023
8. CALPHAD aided mechanical properties screening in full composition space of NbC-TiC-VC-ZrC ultra-high temperature ceramics
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Mingqing Liao, Hongshun Gong, Nan Qu, Fengjiang Wang, Jingchuan Zhu, and Zi-Kui Liu
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General Medicine - Published
- 2023
9. Quantifying the degree of disorder and associated phenomena in materials through zentropy: Illustrated with Invar Fe3Pt
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Shun-Li Shang, Yi Wang, and Zi-Kui Liu
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics - Published
- 2023
10. Integrating data mining and machine learning to discover high-strength ductile titanium alloys
- Author
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Zi Kui Liu, Ying Zhang, Ruihao Yuan, Hongchao Kou, Xidong Hui, Jun Wang, Xingyu Gao, Haifeng Song, Chengxiong Zou, Dongsheng Xu, Xiaoqin Zeng, Jinshan Li, Deye Lin, William Yi Wang, Bin Tang, Xiaodan Wang, and Ma Qian
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Materials science ,Polymers and Plastics ,chemistry.chemical_element ,02 engineering and technology ,computer.software_genre ,Machine learning ,01 natural sciences ,0103 physical sciences ,Work function ,Ductility ,010302 applied physics ,business.industry ,Metals and Alloys ,Titanium alloy ,Charge density ,Fermi energy ,021001 nanoscience & nanotechnology ,Electronic, Optical and Magnetic Materials ,Integrated computational materials engineering ,chemistry ,Ceramics and Composites ,Hardening (metallurgy) ,Artificial intelligence ,Data mining ,0210 nano-technology ,business ,computer ,Titanium - Abstract
Based on the growing power of computational capabilities and algorithmic developments, with the help of data-driven and high-throughput calculations, a new paradigm accelerating materials discovery, design and optimization is emerging. Titanium (Ti) alloys have been chosen herein to highlight an integrated computational materials engineering case study with the aim of improving their strength and ductility. The electronic properties of elemental building blocks were derived from high-throughput first-principles calculations and presented in the form of the Mendeleev periodic table, including their electron work function (Ф), Fermi energy (EF), bonding charge density (Δρ), and lattice distortion energy. The atomic and electronic insights of the composition–structure–property relationships were revealed by a data mining approach, addressing the key features/principles for the design strategies of advanced alloys. Guided by defect engineering, the deformation fault energy and dislocation width were treated as the dominating criteria in improving the ductility. The proposed yield strength model was utilized quantitatively to present the contributions of solid-solution strengthening and grain refinement hardening. Machine learning was used collaboratively with fundamental knowledge and feed back into a new training model, shown to be superior to the empirical molybdenum equivalence method. The results draw a conclusion that the integration of data mining and machine learning will not only generate plausible explanations and address new hypotheses, but also enable the design of strong and ductile Ti alloys in a more efficient and cost-effective way.
- Published
- 2021
11. Computational thermodynamics and its applications
- Author
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Zi Kui Liu
- Subjects
010302 applied physics ,Materials science ,Polymers and Plastics ,media_common.quotation_subject ,Critical phenomena ,Metals and Alloys ,Non-equilibrium thermodynamics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Laws of thermodynamics ,Electronic, Optical and Magnetic Materials ,Power (physics) ,Range (mathematics) ,Metastability ,0103 physical sciences ,Ceramics and Composites ,Statistical physics ,0210 nano-technology ,Function (engineering) ,CALPHAD ,media_common - Abstract
Thermodynamics is a science concerning the state of a system, whether it is stable, metastable or unstable, when interacting with the surroundings. In this overview, fundamentals of thermodynamics are briefly reviewed through the combination of first and second laws of thermodynamics for open and nonequilibrium systems to demonstrate that the reversible equilibrium and irreversible nonequilibrium thermodynamics can be integrated to enhance the power and utilities of thermodynamics. The recent progresses in computational thermodynamics, the remaining challenges, and potential impacts in broad scientific fields are discussed. It is shown that computational thermodynamics enables the modeling of thermodynamics of a state as a function of both external and internal variables and quantitative calculations of a broad range of properties of a multicomponent system in terms of first and second derivatives of energy, including not only equilibrium states when there are no driving forces for any internal processes and but also non-equilibrium states with driving forces for internal processes. Consequently, external constraints such as fixed strain and internal degree of freedoms such as ordering and defects can be described in a coherent framework and applied to materials design. Furthermore, two important but largely overlooked aspects in thermodynamics will be discussed, i.e. the rigorous application of statistical thermodynamics with the probability of configurations and their contributions to system properties, and the applications of second derivatives of energy with respect to either two extensive variables or two potentials or a mixture of them in terms of understanding and predicting emergent behaviors, critical phenomena, kinetic coefficients, and mechanical properties.
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- 2020
12. Metastable trigonal SnP: A promising anode material for potassium-ion battery
- Author
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Jiangxuan Song, Chaofan Zhang, Shun Li Shang, Xingxing Jiao, Jiawei Zhao, Zi Kui Liu, Daniil M. Itkis, and Bing Li
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Materials science ,Composite number ,chemistry.chemical_element ,Potassium-ion battery ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Energy storage ,0104 chemical sciences ,Anode ,chemistry ,Chemical engineering ,Metastability ,General Materials Science ,0210 nano-technology ,Tin ,Carbon - Abstract
Potassium-ion batteries (PIBs) have attracted great interest due to their high-energy-density and low-cost. The lack of stable anode material greatly limits the quick development of PIBs. Phosphorus-metal compounds are regarded as a class of materials with promising prospects as anode material for PIBs with a low operating voltage and high conductivity. Among them, due to the challenging synthesis method, the application of SnP is limited. Herein, a facile approach to synthesize trigonal SnP@C through alloying red phosphorus with tin on carbon material is reported. It is found that carbon substrate can largely reduce vibrational and configurational entropies, playing a critical role on the formation of metastable SnP. When applied as anode in PIBs, the SnP@C composite delivers a high reversible capacity of 478.1 mAh·g−1 at 50 mA g−1 and a stable cycling performance at 1000 mA g−1. The good electrochemical performance is associated with the SnP@C as well as the carbon, which could suppress the phase separation during charge/discharge process to maintain structural stability. This work may open a new avenue for low-cost synthesis of metastable phases for advanced energy storage systems.
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- 2020
13. High-throughput investigations of configurational-transformation-dominated serrations in CuZr/Cu nanolaminates
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Laszlo J. Kecskes, Bin Tang, Jinshan Li, William Yi Wang, Hongchao Kou, Shun Li Shang, Bin Gan, Deye Lin, Yiguang Wang, Xidong Hui, Zhenhai Xia, Peter K. Liaw, Karin A. Dahmen, Yi Wang, Zi Kui Liu, Jun Wang, Xingyu Gao, and Haifeng Song
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Amorphous metal ,Materials science ,Polymers and Plastics ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,Serration ,Devitrification ,Deformation mechanism ,Mechanics of Materials ,Materials Chemistry ,Ceramics and Composites ,Grain boundary ,Dislocation ,Composite material ,0210 nano-technology ,Ductility - Abstract
Metallic amorphous/crystalline (A/C) nanolaminates exhibit excellent ductility while retaining their high strength. However, the underlying physical mechanisms and the resultant structural changes during plastic deformation still remain unclear. In the present work, the structure-property relationship of CuZr/Cu A/C nanolaminates is established through integrated high-throughput micro-compression tests and molecular dynamics simulations together with high-resolution transmission electron microcopy. The serrated flow of nanolaminates results from the formation of hexagonal-close-packed (HCP)-type stacking faults and twins inside the face-centered-cubic (FCC) Cu nano-grains, the body-centered-cubic (BCC)-type ordering at their grain boundaries, and the crystallization of the amorphous CuZr layers. The serration behavior of CuZr/Cu A/C nanolaminates is determined by several factors, including the formation of dense dislocation networks from the multiplication of initial dislocations that formed after yielding, weak-spots-related configurational-transitions and shear-transition-zone activities, and deformation-induced devitrification. The present work provides an insight into the heterogeneous deformation mechanism of A/C nanolaminates at the atomic scale, and mechanistic base for the microstructural design of self-toughening metallic-glass (MG)-based composites and A/C nanolaminates.
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- 2020
14. View and Comments on the Data Ecosystem: 'Ocean of Data'
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Zi Kui Liu
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Environmental Engineering ,Materials science ,General Computer Science ,lcsh:TA1-2040 ,business.industry ,Materials Science (miscellaneous) ,General Chemical Engineering ,Environmental resource management ,General Engineering ,Energy Engineering and Power Technology ,lcsh:Engineering (General). Civil engineering (General) ,business ,Data ecosystem - Published
- 2020
15. An ab initio molecular dynamics exploration of associates in Ba-Bi liquid with strong ordering trends
- Author
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Zi Kui Liu, Hojong Kim, Shun Li Shang, and Jianbo Ma
- Subjects
010302 applied physics ,Work (thermodynamics) ,Materials science ,Polymers and Plastics ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Enthalpy of mixing ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Vertex (geometry) ,Ab initio molecular dynamics ,Bipyramid ,Chemical physics ,Medium range ,0103 physical sciences ,Ceramics and Composites ,Short range order ,0210 nano-technology ,CALPHAD - Abstract
s Fictive associates are widely used to describe and model liquid phases with strong ordering trends. However, little evidence is known about the assumed associates in most cases. In the present work, an ab initio molecular dynamics (AIMD) study is employed to investigate the characters of the Ba-Bi liquid, in which associates have been assumed in existing thermodynamic modeling. It is found that in the Ba rich melt, the Bi atoms are almost completely surrounded by Ba atoms. The Bi-centered coordination polyhedrons are strongly associated to crystalline structures of Ba5Bi3 and Ba4Bi3 with a longer lifetime than other polyhedrons during the AIMD simulations. In addition, these Bi-centered polyhedrons in Ba rich melt connect with each other through vertex, edge, face, and/or bipyramid sharing to form medium range orders (MRO). In the Bi rich melt, the Ba-centered polyhedrons also form MROs, but they are both structurally and compositionally diverse with a shorter lifetime. These findings from AIMD study provide evidences that there exist a strongly ordering Ba4Bi3 associate and a weakly ordering BaBi3 associate in the Ba-Bi liquid. The predicted enthalpy of mixing in the liquid agrees well with the results by the CALPHAD modeling in the literature.
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- 2020
16. Thermodynamic Modeling of the Pd-Zn System with Uncertainty Quantification and its Implication to Tailor Catalysts
- Author
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Rushi Gong, Shun-Li Shang, Hui Sun, Michael J. Janik, and Zi-Kui Liu
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Condensed Matter - Materials Science ,History ,Polymers and Plastics ,General Chemical Engineering ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Chemistry ,Business and International Management ,Industrial and Manufacturing Engineering ,Computer Science Applications - Abstract
Pd-Zn intermetallic catalysts show encouraging combinations of activity and selectivity on well-defined active site ensembles. Thermodynamic description of the Pd-Zn system, delineating phase boundaries, and enumerating site occupancies within intermediate alloy phases, are essential to determining the ensembles of Pd-Zn atoms as a function of composition and temperature. Combining the present extensive first-principles calculations based on density functional theory (DFT) and available experimental data, the Pd-Zn system was remodeled using the CALculation of PHAse Diagrams (CALPHAD) approach. High throughput modeling tools with uncertainty quantification, i.e., ESPEI and PyCalphad, were incorporated in the phase analysis. The site occupancies across the {\gamma}-phase composition region were given special attention. A four-sublattice model was used for the {\gamma}-phase owing to its four Wyckoff positions, i.e., the outer tetrahedral (OT) site 8c, the inner tetrahedral (IT) site 8c, the octahedral (OH) 12e, and the cuboctahedral (CO) site 24g. The site fractions of Pd and Zn calculated from the present thermodynamic model show the occupancy preference of Pd in the OT and OH sublattices in agreement with experimental observations. The force constants obtained from DFT-based phonon calculations further supports the tendency of Pd occupying the OH sublattice compared with the IT and CO sublattice. The catalytic assembles changing from Pd monomers (Pd1) to trimers (Pd3) on the surface of the {\gamma}-phase is attributed to the increase of Pd occupancy in the OH sublattice., Comment: 12 figures
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- 2022
17. Ab Initio Studies on Structural and Thermodynamic Properties of Magnetic Fe
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Songge Yang, Yi Wang, Zi-Kui Liu, and Yu Zhong
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
18. Quantifying the Degree of Disorder and Associated Phenomena in Materials Through Zentropy: Illustrated with Invar Fe 3Pt
- Author
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Shun-Li Shang, Yi Wang, and Zi-Kui Liu
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
19. Thermodynamic Re-modeling of the Yb-Sb System Aided by First-Principles Calculations
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Jorge Paz Soldan Palma, XiaoYu Chong, Yi Wang, Shun-Li Shang, and Zi-Kui Liu
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History ,Polymers and Plastics ,General Chemical Engineering ,General Chemistry ,Business and International Management ,Industrial and Manufacturing Engineering ,Computer Science Applications - Published
- 2022
20. Thermodynamic Modeling with Uncertainty Quantification Using the Modified Quasichemical Model in Quadruplet Approximation: Implementation into PyCalphad and ESPEI
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Jorge Paz Soldan Palma, Rushi Gong, Brandon J. Bocklund, Richard Otis, Max Poschmann, Markus Piro, Tatiana G. Levitskaia, Shenyang Hu, Nathan D. Smith, Yi Wang, Hojong Kim, Zi-Kui Liu, and Shun-Li Shang
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
21. An additively manufactured γ-based high Nb-TiAl composite via coherent interface regulation
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Hui Xue, Yongfeng Liang, Hui Peng, Yanli Wang, Shun-Li Shang, Zi-Kui Liu, and Junpin Lin
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys ,General Materials Science ,Condensed Matter Physics - Published
- 2023
22. Study on impact of Cr and Mo on diffusion of H in 2.25Cr1Mo steel using first-principle calculations
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Chao Fang, Zi Kui Liu, Wenyi Wang, Jianzhu Cao, Shun Li Shang, and Chuan Li
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Nuclear and High Energy Physics ,Materials science ,Hydrogen ,Thermodynamics ,chemistry.chemical_element ,02 engineering and technology ,Activation energy ,021001 nanoscience & nanotechnology ,Thermal diffusivity ,01 natural sciences ,010305 fluids & plasmas ,Nuclear Energy and Engineering ,chemistry ,Impurity ,0103 physical sciences ,Tetrahedron ,First principle ,General Materials Science ,Tritium ,Density functional theory ,0210 nano-technology - Abstract
Chrome-molybdenum steel (2.25Cr1Mo steel) is one of the main materials of a steam generator (SG) in high-temperature reactor-pebblebed modules (HTR-PM). It is essential to analyze the source term of tritium in this material, because the behavior of tritium in a SG is important for performing source term analysis in normal and accident conditions. In this article, the diffusion behavior of H atom in 2.25Cr1Mo steel was calculated to estimate the diffusivity of tritium using first-principles density functional theory. To develop and simplify the model of hydrogen diffusion in 2.25Cr1Mo steel, the impact of Cr and Mo on the diffusion of hydrogen in bcc-Fe were first calculated, all the possible diffusion paths were considered, and the minimum energy path was obtained. The diffusion activation energy and pre-exponential factor of the diffusion coefficient were obtained from Vienna Ab initio Simulation Package combined with the climbing image-nudged elastic band method. The results indicate that the minimum energy path for the impurity H atom is from one tetrahedral interstitial site to an adjacent tetrahedral interstitial site. The function of the diffusion coefficient of H in 2.25Cr1Mo steel with temperature T can be expressed as D = 1.486 × 10 − 7 × ( − 16.350 kJ / mol RT ) (m2/s). The diffusion coefficient of our calculation and some of the previous experiments have an excellent quantitative agreement, which indicates the reliability of our crystalline model and the practicability of the present theoretical approach. More importantly, the computational results in this work can be treated as a good screening method to collect reasonable experimental data, which will provide a good reference for tritium source term evaluation in the SG of the HTR-PM.
- Published
- 2019
23. Ordering in liquid and its heredity impact on phase transformation of Mg-Al-Ca alloys
- Author
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Jiang You, Cheng Wang, Shun-Li Shang, Yipeng Gao, Hong Ju, Hong Ning, Yi Wang, Hui-Yuan Wang, and Zi-Kui Liu
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Mechanics of Materials ,Metals and Alloys - Published
- 2021
24. Density functional theory-informed dislocation density hardening within crystal plasticity: Application to modeling deformation of Ni polycrystals
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Adnan Eghtesad, John D. Shimanek, Shun-Li Shang, Ricardo Lebensohn, Marko Knezevic, Zi-Kui Liu, and Allison M. Beese
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Computational Mathematics ,General Computer Science ,Mechanics of Materials ,General Physics and Astronomy ,General Materials Science ,General Chemistry - Published
- 2022
25. A high-efficient strain-stress method for calculating higher-order elastic constants from first-principles
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Mingqing Liao, Yong Liu, Fei Zhou, Tianyi Han, Danni Yang, Nan Qu, Zhonghong Lai, Zi-Kui Liu, and Jingchuan Zhu
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Hardware and Architecture ,General Physics and Astronomy - Published
- 2022
26. Atomic-scale unveiling of strengthening in interstitial solid soluted Nb-rich TiAl alloys
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Hui Xue, Yongfeng Liang, Shun-Li Shang, Zi-Kui Liu, and Junpin Lin
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Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys - Published
- 2022
27. Insight into ideal shear strength of Ni-based dilute alloys using first-principles calculations and correlational analysis
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John Shimanek, Allison Beese, Shun-Li Shang, and Zi-Kui Liu
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Condensed Matter::Soft Condensed Matter ,Condensed Matter - Materials Science ,Condensed Matter::Materials Science ,Computational Mathematics ,General Computer Science ,Mechanics of Materials ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,General Physics and Astronomy ,General Materials Science ,General Chemistry - Abstract
The present work examines the effect of alloying elements (denoted X) on the ideal shear strength for 26 dilute Ni-based alloys, Ni$_{11}$X, as determined by first-principles calculations of pure alias shear deformations. The variations in ideal shear strength are quantitatively explored with correlational analysis techniques, showing the importance of atomic properties such as size and electronegativity. The shear moduli of the alloys are affirmed to show a strong linear relationship with their ideal shear strengths, while the shear moduli of the individual alloying elements were not indicative of alloy shear strength. Through combination with available ideal shear strength data on Mg alloys, a potential application of the Ni alloy data is demonstrated in the search for a set of atomic features suitable for machine learning applications to mechanical properties. As another illustration, the predicted Ni ideal shear strengths play a key role in a predictive multiscale framework for deformation behavior of single crystal alloys at large strains, as shown by simulated stress-strain curves., Comment: Associated data at https://doi.org/10.5281/zenodo.5497912
- Published
- 2022
28. Electrochemical recovery of Nd using liquid metals (Bi and Sn) in LiCl-KCl-NdCl3
- Author
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Sanghyeok Im, Nathan D. Smith, Stephanie Castro Baldivieso, Jarrod Gesualdi, Zi-Kui Liu, and Hojong Kim
- Subjects
General Chemical Engineering ,Electrochemistry - Published
- 2022
29. High-throughput thermodynamic calculations of phase equilibria in solidified 6016 Al-alloys
- Author
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Xuanhui Qu, Zi Kui Liu, Xue Jiang, Xin Wang, Cong Zhang, Haiqing Yin, and Ruijie Zhang
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General Computer Science ,Computer science ,business.industry ,General Physics and Astronomy ,02 engineering and technology ,General Chemistry ,Python (programming language) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Computational science ,Visualization ,Computational Mathematics ,Software ,Mechanics of Materials ,Phase composition ,General Materials Science ,0210 nano-technology ,Phase fraction ,business ,computer ,computer.programming_language - Abstract
In the present work, high-throughput calculation (HTC) method is performed to obtain the phase equilibria of solidified 6016 Al-alloys. The calculations of primary phase fraction, precipitates fraction and phase composition are realized based on the Scheil-Gulliver solidification model of Thermo-Calc software, and the entire composition ranges of standard 6016 Al-alloy is taken into account. A Python-based program called Automatic Execution and Extraction Tasks (AEET) is developed, it automatically generate the commands of calculations, execute the Thermo-Calc software and then extract the key data of output files. The obtained results are listed in an Excel file, which is convenient for the subsequent visualization analysis and machine learning. Several criteria are combined to filter the appropriate compositions of industrial 6016 Al-alloys, providing a valuable guidance to the experimentalists and avoiding unnecessary trial-and-error tests. This HTC approach is not limited to the solidification modelings; it can be extended to any kinds of thermodynamic and kinetic calculations.
- Published
- 2019
30. An alternative approach to predict Seebeck coefficients: Application to La3−xTe4
- Author
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Yongjie Hu, Samad Firdosy, Yi Wang, Long Qing Chen, Vilupanur A. Ravi, Xiaoyu Chong, Zi Kui Liu, Kurt Star, Jean-Pierre Fleurial, Fivos Drymiotis, and Shun Li Shang
- Subjects
010302 applied physics ,Materials science ,Condensed matter physics ,Phonon ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Thermoelectric materials ,01 natural sciences ,Thermal expansion ,Condensed Matter::Materials Science ,symbols.namesake ,Mechanics of Materials ,Seebeck coefficient ,0103 physical sciences ,Thermal ,symbols ,Fermi–Dirac statistics ,General Materials Science ,Charge carrier ,0210 nano-technology ,Electrochemical potential - Abstract
A thermodynamic understanding of Seebeck coefficient was demonstrated in terms of electrochemical potential. It divided the contributions to the Seebeck coefficient into two contributions: the effect of thermal electronic excitations due to Fermi distribution and the effect of charge carrier gradient due to thermal expansion. The procedure is illustrated within the rigid band approximation in terms of the electronic density-of-states and the quasiharmonic approximation in terms of the phonon density-of-states. Numerical results were given using the n-type high temperature thermoelectric material La3-xTe4 at x = 0, 0.25, and 0.33 as the prototype at a variety of carrier concentrations.
- Published
- 2019
31. First-principles lattice dynamics and thermodynamic properties of pre-perovskite PbTiO3
- Author
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Yi Wang, Yanzhou Ji, Ce-Wen Nan, Long Qing Chen, Zi Kui Liu, and Meng Jun Zhou
- Subjects
010302 applied physics ,Phase transition ,Materials science ,Polymers and Plastics ,Condensed matter physics ,Band gap ,Phonon ,Metals and Alloys ,Nanowire ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Tetragonal crystal system ,symbols.namesake ,0103 physical sciences ,Ceramics and Composites ,symbols ,0210 nano-technology ,Debye model ,Phase diagram - Abstract
It was recently found that nanowires of PbTiO3 synthesized through an intermediate pre-perovskite phase exhibit enhanced spontaneous polarization. Here we investigated the pre-perovskite PbTiO3 (PP-PTO) nanowire phase at finite temperatures employing first-principles quasiharmonic calculations. We calculated its band gap, phonon dispersions, phonon density of states, Debye temperature, and thermodynamic properties. The corresponding calculations for cubic and tetragonal PbTiO3 were also carried out for comparison. In the current calculations, the amount of imaginary frequencies associated with the ideal cubic PTO structure, i.e., a cubic cell shape with ion positions at the ideal cubic perovskite lattice sites, was decreased to a negligible level by employing a constrained cubic structure, a structure with the same cubic cell shape as the ideal cubic PTO structure but allowing the ion positions to relax to thermodynamically more stable tetragonal positions at 0 K. In contrast to the general observation that a higher volume phase would have relatively higher entropy, it is found that the PP-PTO phase possesses the lowest entropy while having the largest volume compared to cubic and tetragonal PbTiO3 phases. Furthermore, the temperature-pressure phase diagram for the three PbTiO3 phases was obtained, which demonstrates that PP-PTO could be stabilized under a large volume or a negative pressure. This study provides insights to experimentally synthesizing the PP-PTO phase and to better understanding its phase transition into the converted tetragonal PbTiO3 nanowires with enhanced piezoelectric and ferroelectric properties.
- Published
- 2019
32. Thermodynamic modeling of the Si-Y system aided by first-principles and phonon calculations
- Author
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Zhao Xushan, Mao You Chu, Jian Yun Shen, Shun Li Shang, Zhao Zhang, Zi Kui Liu, and Kun Li
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010302 applied physics ,Materials science ,Phonon ,General Chemical Engineering ,0211 other engineering and technologies ,Thermodynamics ,02 engineering and technology ,General Chemistry ,01 natural sciences ,Computer Science Applications ,0103 physical sciences ,Homogeneity (physics) ,Binary system ,CALPHAD ,021102 mining & metallurgy ,Phase diagram ,Eutectic system - Abstract
Thermodynamic modeling of the Si-Y binary system has been performed by the CALPHAD (CALculation of PHAse Diagram) method based on phase diagram and thermochemical data in the literature combined with Gibbs energies of end-members of compounds predicted by first-principles phonon calculations. In particular, non-stoichiometric compounds Si2Y and Si3Y5 are modelled to accommodate their homogeneity ranges in terms of two-sublattice models (Si,Y)2(Si,Y) and (Si)3(Si,Y)5, respectively. Formation of SiY is treated as a peritectic reaction according to experimental results, instead of an eutectic one as described in the previous models. The calculated phase equilibriums and thermodynamic properties are in a satisfactory agreement with available experimental data.
- Published
- 2019
33. Synthesis and understanding of Na11Sn2PSe12 with enhanced ionic conductivity for all-solid-state Na-ion battery
- Author
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Hemant P. Yennawar, Shun Li Shang, Donghai Wang, Yue Gao, Thomas E. Mallouk, Haw Tyng Huang, Zhaoxin Yu, Yuguang C. Li, Daiwei Wang, Zi Kui Liu, and Guoxing Li
- Subjects
Battery (electricity) ,Materials science ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,02 engineering and technology ,Electrolyte ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Alkali metal ,Thermal conduction ,01 natural sciences ,0104 chemical sciences ,Ion ,Chemical engineering ,Ionic conductivity ,General Materials Science ,Bond energy ,0210 nano-technology - Abstract
All-solid-state Na-ion batteries (NIBs) that incorporate nonflammable solid-state electrolytes and an inexhaustible alkali metal offer a potential solution to the safety and cost concerns associated with conventional Li-ion batteries that use liquid electrolytes. Na-ion solid-state electrolytes (SSEs) with high ionic conductivity are the key to success for all-solid-state NIBs. Here, we report a new Na-ion SSE, Na11Sn2PSe12, with a superior grain conductivity of 3.04 mS cm−1 and a total ionic conductivity of 2.15 mS cm−1 at 25 °C. Single-crystal X-ray diffraction, first-principles phonon calculations, and the proposed bonding energy model indicate that its superior ionic conductivity stems from the presence of a high density of dispersive Na+ vacancies, three-dimensional Na-ion conduction pathways, and a low bonding energy of the Na+ ion with its neighboring atoms. Na11Sn2PSe12 is used for the first time as the electrolyte in all-solid-state Na-Sn/TiS2 battery cell, which shows excellent rate performance and delivers a high reversible capacity of 66.2 mAh (g of TiS2)−1 after 100 cycles with cycling retention of 88.3% at a rate of 0.1 C at room temperature.
- Published
- 2019
34. From random stacking faults to polytypes: A 12-layer NiSn4 polytype
- Author
-
Christian Schimpf, P. Kalanke, Zi Kui Liu, C. Wolf, Shun Li Shang, Andreas Leineweber, and Hanka Becker
- Subjects
Diffraction ,Materials science ,Mechanical Engineering ,Diffusion ,Metals and Alloys ,Stacking ,02 engineering and technology ,Crystal structure ,Atmospheric temperature range ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Tetragonal crystal system ,Crystallography ,Mechanics of Materials ,Group (periodic table) ,Materials Chemistry ,Orthorhombic crystal system ,0210 nano-technology - Abstract
NiSn4 grows in diffusion couples (Ni plates with electrodeposited Sn) in a temperature range from room temperature up to 353 K. Previously, the crystal structure of NiSn4 grown at ambient temperature was identified to be an intermediate stacking variant between the orthorhombic PtSn4-type and the tetragonal β-IrSn4-type structure, with a slight tendency towards the tetragonal type (Schimpf et al., Mater. Design 109 (2016) 324–333). Now it is reported that NiSn4 forming at 333 K and above, exhibits a 12-layer polytype (space group P42/nbc, a = b = 6.250 A, c = 69.00 A) due to ordered incorporation of stacking faults into the structure. This NiSn4 structure was derived by comparison of its diffraction patterns with those of the exhaustively generated NiSn4 polytypes. First-principles calculations on a series of selected NiSn4 polytypes demonstrate that the experimentally observed polytype is energetically favoured as compared to others.
- Published
- 2019
35. Thermodynamic properties and phase stability of the Ba-Bi system: A combined computational and experimental study
- Author
-
Zi Kui Liu, Pin-Wen Guan, Jinming Liu, Cassie Marker, Shun Li Shang, Nicole E. Orabona, Nathan D. Smith, and Hojong Kim
- Subjects
Phase transition ,Materials science ,Mechanical Engineering ,Metals and Alloys ,Thermodynamics ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Gibbs free energy ,symbols.namesake ,Mechanics of Materials ,Phase (matter) ,Materials Chemistry ,symbols ,Density functional theory ,Molten salt ,0210 nano-technology ,CALPHAD ,Phase diagram ,Eutectic system - Abstract
The thermodynamic properties and phase stability of the Ba-Bi system are investigated computationally and experimentally in the present work. The enthalpies of formation and the finite temperature thermodynamic properties of seven compounds are predicted by first-principles calculations based on density functional theory (DFT), indicating five compounds (BaBi3, Ba11Bi10, Ba4Bi3, Ba5Bi3, and Ba2Bi) to be stable. Phase relations at 773 K and 858 K with composition xBa = 0.90 are established by isothermal annealing and powder X-ray diffraction (XRD) to clarify the previously observed phase transition at 796 K. The extremely low chemical activity of Ba in liquid for a wide range of temperatures and compositions indicates very strong short-range ordering in the liquid phase which is modeled in the present work by introducing the Ba4Bi3 and BaBi3 associates in the liquid phase. Both thermodynamic and phase equilibrium data are then used to evaluate the model parameters in Gibbs energy functions of the five stable compounds and three solution phases of liquid, bcc, and rhombohedral phases by the CALPHAD (CALculation of PHAse Diagram) technique. The present work shows that the Ba-Bi system consists of three eutectic reactions, two peritectic reactions, one peritectoid reaction, and two congruent reactions, as well as that the concentrations of associates are very high in the liquid phase with very low concentration of atomic Ba, which provides the fundamental understanding as to why Bi can be used to remove Ba ions from molten salt solutions.
- Published
- 2019
36. Thermodynamic re-modelling of the Cu–Nb–Sn system: Integrating the nausite phase
- Author
-
Jonas Lachmann, Mario J. Kriegel, Andreas Leineweber, Shun-Li Shang, and Zi-Kui Liu
- Subjects
General Chemical Engineering ,General Chemistry ,Computer Science Applications - Published
- 2022
37. First-principles calculations and thermodynamic modelling of long periodic stacking ordered (LPSO) phases in Mg-Al-Gd
- Author
-
Austin Ross, Hongyeun Kim, Zi Kui Liu, Yi Wang, Laszlo J. Kecskes, and Shun Li Shang
- Subjects
010302 applied physics ,Work (thermodynamics) ,Materials science ,Phase stability ,Alloy ,Stacking ,Thermodynamics ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Mole fraction ,01 natural sciences ,0103 physical sciences ,Cluster (physics) ,engineering ,General Materials Science ,0210 nano-technology ,CALPHAD ,Phase diagram - Abstract
In the present work, thermodynamic modelling of four long periodic stacking ordered (LPSO) phases, i.e., 10H, 18R, 14H, and 24R, in the Mg-Al-Gd system was performed using the CALPHAD (calculation of phase diagram) approach with input from the present first-principles calculations and experimental data in the literature. Sublattice models were developed to describe these LPSO phases. Especially, an L12-type clusters in the FCC stacking layers of LPSO phases and the atomic occupancy in the center of L12 cluster were considered based on experimental observations and energetics from first-principles calculations. The calculated phase equilibrium results are in good agreement with experiments about the phase stability of 14H and 18R and the mole fraction of Gd and Al in these LPSO phases. The present modeling provides a new approach to describe the thermodynamic properties of LPSO phases and can be applied to other alloy systems.
- Published
- 2018
38. Phase field simulation of the lamellar precipitation in the TiC-ZrC system
- Author
-
Zelin Luo, Yong Du, Sai Tang, Yingbiao Peng, Zi Kui Liu, and Hong Mao
- Subjects
Work (thermodynamics) ,Materials science ,Field (physics) ,Precipitation (chemistry) ,020502 materials ,Process Chemistry and Technology ,Elastic energy ,Thermodynamics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Stress field ,0205 materials engineering ,Phase (matter) ,Materials Chemistry ,Ceramics and Composites ,Lamellar structure ,0210 nano-technology - Abstract
TiC-ZrC system with a high hardness is a promising material being widely used in processing and manufacturing industries. The effect of elastic strain on the formation of lamellar microstructure was investigated in the present work through the methodology combing our thermodynamic data and two-dimensional Cahn-Hilliard/elastic strain energy model. It is shown that elastic induced lattice distortion and stress field at the boundaries affect the precipitation process. The simulation results agree well with the previous experimental results in terms of the variation of the periodicity for the elemental distribution and the morphology of regularity for lamellar microstructure. It is demonstrated that phase field method coupled with thermodynamic database can make precipitation models to access those proven thermodynamic models, which can be applied to simulation of various material systems.
- Published
- 2018
39. Phase field simulation of the phase separation in the TiC-ZrC-WC system
- Author
-
Hong Mao, Yingbiao Peng, Zi Kui Liu, Yong Du, Zelin Luo, Wensheng Liu, Yafei Pan, Sai Tang, and Yuling Liu
- Subjects
Microstructural evolution ,Materials science ,Spinodal decomposition ,020502 materials ,General Chemical Engineering ,Thermodynamics ,02 engineering and technology ,General Chemistry ,Field simulation ,021001 nanoscience & nanotechnology ,Microstructure ,Space (mathematics) ,Computer Science Applications ,Matrix (mathematics) ,Distribution (mathematics) ,0205 materials engineering ,Phase (matter) ,0210 nano-technology - Abstract
The phase separation in the ZrC-TiC-WC pseudo-ternary system is investigated by actualizing a model based on Cahn-Hilliard equation in three-dimensional space. The simulation results show the solute diffusion of the three elements at different time and temperature, and the results are compared with the experimental results. The microstructural evolution is investigated by performing a statistical analysis during the spinodal decomposition. A sub-circular pattern is observed with the Ti- and W-rich regions embedded in the Zr rich matrix and the approximately the same shape and distribution. The number of Ti- and W-rich regions decreases and their averages size increases with time. The time required for completion of phase separation decreases with the increase of temperature. The simulation result of the phase separation in the ZrC-TiC-WC pseudo-ternary system is very similar to the experimental observation in element distribution. The laws and characteristics of microstructure evolution are well predicted in the ZrC-TiC-WC pseudo-ternary system.
- Published
- 2018
40. Thermodynamic Properties of the Nd-Bi System Via Emf Measurements, DFT Calculations, and CALPHAD Modeling
- Author
-
Hui Sun, Zi Kui Liu, Timothy Lichtenstein, Nathan D. Smith, Brandon Bocklund, Adam M. Krajewski, Sanghyeok Im, Shun Li Shang, and Hojong Kim
- Subjects
Activity coefficient ,Materials science ,Differential scanning calorimetry ,Electromotive force ,Thermodynamics ,Density functional theory ,Liquidus ,EMF measurement ,CALPHAD ,Phase diagram - Abstract
Thermodynamic properties of the Nd-Bi system were investigated using a combination of experimental measurements, first-principles calculations based on density functional theory (DFT), machine learning (ML) predictions, and calculation of phase diagrams (CALPHAD) modeling. The electromotive force (emf) of Nd-Bi alloys in molten LiCl-KCl-NdCl3 at 773–973 K was measured via coulometric titration of Nd in Bi for the determination of thermochemical properties such as activity coefficients and solubilities of Nd in Bi. A new peritectic reaction of [liquid + NdBi2 = Nd3 Bi7] at 774 K was confirmed using differential scanning calorimetry, structural (X-ray diffraction), and microstructural (scanning electron microscopy) analyses. The unknown crystal structure of NdBi2 was suggested to be a mixture of the anti-La2Sb configuration and the La2Te-type configuration based on ML predictions for over 26,000 AB2-type configurations together with DFT-based verifications. Using the newly acquired experimental data and DFT-based calculations, the thermodynamic description of the Nd-Bi system was remodeled, and a more complete Nd-Bi phase diagram was calculated, including the Nd3Bi7 compound, invariant transition reactions, and liquidus temperatures.
- Published
- 2021
41. Design of an additively manufactured functionally graded material of 316 stainless steel and Ti-6Al-4V with Ni-20Cr, Cr, and V intermediate compositions
- Author
-
Lourdes D. Bobbio, Brandon Bocklund, Emrah Simsek, Ryan T. Ott, Matt J. Kramer, Zi-Kui Liu, and Allison M. Beese
- Subjects
Biomedical Engineering ,General Materials Science ,Engineering (miscellaneous) ,Industrial and Manufacturing Engineering - Published
- 2022
42. Extensible Structure-Informed Prediction of Formation Energy with Improved Accuracy and Usability Employing Neural Networks
- Author
-
Jonathan W. Siegel, Zi Kui Liu, Jinchao Xu, and Adam M. Krajewski
- Subjects
General Computer Science ,Computer science ,Generalization ,FOS: Physical sciences ,General Physics and Astronomy ,Overfitting ,computer.software_genre ,03 medical and health sciences ,0302 clinical medicine ,General Materials Science ,030304 developmental biology ,Structure (mathematical logic) ,Condensed Matter - Materials Science ,0303 health sciences ,Artificial neural network ,business.industry ,Materials Science (cond-mat.mtrl-sci) ,Usability ,General Chemistry ,Computational Physics (physics.comp-ph) ,Computational Mathematics ,Mechanics of Materials ,030220 oncology & carcinogenesis ,Test set ,Data mining ,User interface ,business ,Physics - Computational Physics ,computer ,Energy (signal processing) - Abstract
In recent years, numerous studies have employed machine learning (ML) techniques to enable orders of magnitude faster high-throughput materials discovery by augmentation of existing methods or as standalone tools. In this paper, we introduce a new neural network-based tool for the prediction of formation energies based on elemental and structural features of Voronoi-tessellated materials. We provide a self-contained overview of the ML techniques used. Of particular importance is the connection between the ML and the true material-property relationship, how to improve the generalization accuracy by reducing overfitting, and how new data can be incorporated into the model to tune it to a specific material system. In the course of this work, over 30 novel neural network architectures were designed and tested. This lead to three final models optimized for (1) highest test accuracy on the Open Quantum Materials Database (OQMD), (2) performance in the discovery of new materials, and (3) performance at a low computational cost. On a test set of 21,800 compounds randomly selected from OQMD, they achieve mean average error (MAE) of 28, 40, and 42 meV/atom respectively. The second model provides better predictions on materials far from ones reported in OQMD, while the third reduces the computational cost by a factor of 8. We collect our results in a new open-source tool called SIPFENN (Structure-Informed Prediction of Formation Energy using Neural Networks). SIPFENN not only improves the accuracy beyond existing models but also ships in a ready-to-use form with pre-trained neural networks and a user interface.
- Published
- 2020
43. Thermodynamic properties of the Nd-Bi system via emf measurements, DFT calculations, machine learning, and CALPHAD modeling
- Author
-
Shun Li Shang, Brandon Bocklund, Sanghyeok Im, Adam M. Krajewski, Nathan D. Smith, Hojong Kim, Timothy Lichtenstein, Hui Sun, and Zi Kui Liu
- Subjects
Activity coefficient ,Materials science ,Polymers and Plastics ,Electromotive force ,business.industry ,Metals and Alloys ,Liquidus ,EMF measurement ,Machine learning ,computer.software_genre ,Electronic, Optical and Magnetic Materials ,Differential scanning calorimetry ,Ceramics and Composites ,Density functional theory ,Artificial intelligence ,business ,computer ,CALPHAD ,Phase diagram - Abstract
Thermodynamic properties of the Nd-Bi system were investigated using a combination of experimental measurements, first-principles calculations based on density functional theory (DFT), data mining and machine learning (DM + ML) predictions, and calculation of phase diagrams (CALPHAD) modeling. The electromotive force (emf) of Nd-Bi alloys in molten LiCl-KCl-NdCl3 at 773–973 K was measured via coulometric titration of Nd into Bi for the determination of thermochemical properties such as activity coefficients and solubilities of Nd in Bi. A new peritectic reaction of [liquid + NdBi2 = Nd3Bi7] at 774 K was confirmed using differential scanning calorimetry, structural (X-ray diffraction), and microstructural (scanning electron microscopy) analyses. The unknown crystal structure of NdBi2 was suggested to be a mixture of the anti-La2Sb configuration and the La2Te-type configuration based on ML predictions for over 26,000 data-mined AB2-type configurations together with DFT-based verifications. Using the newly acquired experimental data and DFT-based calculations, the thermodynamic description of the Nd-Bi system was remodeled, and a more complete Nd-Bi phase diagram was calculated, including the Nd3Bi7 compound, invariant transition reactions, and liquidus temperatures.
- Published
- 2022
44. A first-principles based description of the Hf-Ni system supported by high-temperature synchrotron experiments
- Author
-
Matthew J. Kramer, Thomas Gheno, Xuan L. Liu, Zi Kui Liu, Pravat Kumar Ray, Shun Li Shang, Greta Lindwall, Bi Cheng Zhou, Brian Gleeson, and Austin Ross
- Subjects
010302 applied physics ,Work (thermodynamics) ,Materials science ,Diffusion ,Thermodynamics ,02 engineering and technology ,Crystal structure ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Synchrotron ,law.invention ,law ,Phase (matter) ,0103 physical sciences ,Binary system ,Physical and Theoretical Chemistry ,Solubility ,0210 nano-technology ,Instrumentation ,CALPHAD - Abstract
Hf-Ni is an important binary system for high temperature alloys and shape memory alloys which has been investigated several times in the literature but often using samples of Hf contaminated by Zr. The thermodynamics of this system are remodeled in this work based on first-principles calculations and additional experiments using Hf with relatively low Zr contamination (0.25 wt. %). Diffusion couples in the Ni-rich portion of the Hf-Ni system heat treated at 1173, 1273 and 1373 K are used to measure phase stability and Hf solubility in the fcc phase. The solubility observed in fcc Ni from Ni/Ni50Hf50 (at.%) diffusion couples is larger than that observed in previous experiments. These results are the only source fit to during modeling of the fcc solubility to mitigate effects from Zr contamination. Data in the literature suggests that the high temperature crystal structure of the B33 NiHf phase is, in fact, the B2 structure. High temperature synchrotron measurements provide confirmation of this crystal structure. Modeling of the B2 phase was aided by first-principles calculations using special quasi-random structures (SQS). The present CALPHAD model will prove useful when designing shape memory alloys containing Hf and when modeling the Hf activity in Ni-base high temperature alloys.
- Published
- 2018
45. A comprehensive first-principles study of solute elements in dilute Ni alloys: Diffusion coefficients and their implications to tailor creep rate
- Author
-
Zi Kui Liu, Chelsey Z. Hargather, and Shun Li Shang
- Subjects
010302 applied physics ,Ionic radius ,Materials science ,Polymers and Plastics ,Metals and Alloys ,Thermodynamics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Thermal diffusivity ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Superalloy ,symbols.namesake ,Creep ,0103 physical sciences ,Ceramics and Composites ,Compressibility ,symbols ,Local-density approximation ,0210 nano-technology ,Debye model ,Stacking fault - Abstract
Diffusion regulates a vast number of materials properties and phenomena such as creep, the focus of the present work. However, a deep understanding of the effect of how each alloying element in a Ni-base superalloy affects properties such as diffusion and creep is far from complete. Here, we report temperature-dependent dilute solute diffusion coefficients and their implications to tailor the creep rate for 26 transition metal solute elements, X's, in fcc Ni using first-principles calculations. Calculations are performed using the five-frequency model for dilute solute diffusion and the nudged elastic band method within the local density approximation. Thermodynamic properties at finite temperatures for all configurations are calculated using the quasi-harmonic Debye model. In general, the fastest diffusing solute elements in Ni are found at the left side of the periodic table and the slowest diffusing solute elements are found in group VIIB. In particular, the present work indicates that the diffusivity of the dilute solute elements is correlated to the compressibility of each solute element on the respective Ni31X supercell, and not as strongly to the ionic radius of the solute elements, as previously suggested. Finally, results from the diffusivity study are combined with the previous results of elastic constants and stacking fault energies, and hence, a relative creep rate ratio for these 26 solute elements is modeled. It is shown that in most cases, slower diffusing solute elements provide the most creep resistance. This is true even at higher temperatures, due mainly to the solute's strong bonding with Ni atoms in the host lattice.
- Published
- 2018
46. Elastic properties of long periodic stacking ordered phases in Mg-Gd-Al alloys: A first-principles study
- Author
-
Hongyeun Kim, Zi Kui Liu, Laszlo J. Kecskes, Shun Li Shang, William Yi Wang, and Kristopher A. Darling
- Subjects
010302 applied physics ,Work (thermodynamics) ,Materials science ,Condensed matter physics ,Mg alloys ,Mechanical Engineering ,Metals and Alloys ,Stacking ,Stiffness ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Mechanics of Materials ,0103 physical sciences ,Atom ,Materials Chemistry ,Cluster (physics) ,medicine ,medicine.symptom ,0210 nano-technology ,Ductility - Abstract
Long periodic stacking ordered (LPSO) phases have been reported to enhance the strength and ductility of Mg alloys due to their high elastic properties. In the present work, the effects of atomic arrangements in terms of Gd-Al L12-type clusters on LPSOs' elastic properties in the Mg-Gd-Al system were studied using first-principles calculations. Four types of LPSO phases (10H, 18R, 14H, and 24R) were investigated with and without an interstitial atom in the center of the L12-type clusters. It was observed that the elastic stiffness components of the LPSO phases such as C11, C33 and C66 are closely related to the bonding distances of L12 cluster. Furthermore, the interstitial atom within the L12 cluster plays an important role in affecting the elastic stiffness constants of LPSOs, resulting in an increase of C11 and C33 due to the bonding distances of L12 cluster.
- Published
- 2018
47. Thermodynamic modeling of the La-Te system aided by first-principles calculations
- Author
-
Zi Kui Liu, Jorge Paz Soldan Palma, Yongjie Hu, Yi Wang, Vilupanur A. Ravi, Samad Firdosy, Kurt Star, and Jean-Pierre Fleurial
- Subjects
010302 applied physics ,Materials science ,Phase equilibrium ,General Chemical Engineering ,Intermetallic ,Thermodynamics ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Computer Science Applications ,0103 physical sciences ,Homogeneity (physics) ,Condensed Matter::Strongly Correlated Electrons ,Density functional theory ,Binary system ,0210 nano-technology ,CALPHAD ,Stoichiometry ,Phase diagram - Abstract
A complete thermodynamic description of the La-Te binary system is developed by means of CALculation of PHAse Diagram (CALPHAD) method in combination with available experimental data in the literature and the present first-principles calculations based on density functional theory. The intermetallic phases with homogeneity ranges, La3-xTe4 and LaTe2-x, are modeled using a two-sublattice (La,Va)3(Te)4 model and a three-sublattice (La)1(Te)1(Te,Va)1 model based on their structure features, respectively. The intermetallic phases, LaTe and LaTe3, are treated as stoichiometric compounds. The thermodynamic properties of the intermetallic compounds and their corresponding end members at finite temperatures are predicted using first-principles quasi-harmonic approach. The associate solution model is used to describe the short-range ordering behavior of the liquid phase. The calculated phase diagram agrees well with the available phase equilibrium data in the literature.
- Published
- 2018
48. The Thermodynamic Database Database
- Author
-
Zi Kui Liu, Axel van de Walle, and Chiraag Nataraj
- Subjects
010302 applied physics ,Service (systems architecture) ,Focus (computing) ,Database ,business.industry ,Computer science ,General Chemical Engineering ,Materials informatics ,02 engineering and technology ,General Chemistry ,Scientific literature ,Information repository ,021001 nanoscience & nanotechnology ,computer.software_genre ,01 natural sciences ,Computer Science Applications ,Software ,0103 physical sciences ,Key (cryptography) ,0210 nano-technology ,business ,CALPHAD ,computer - Abstract
This paper describes an effort to organize the condensed phases thermodynamic data freely available in electronic form within the scientific literature through the design of a special-purpose search engine indexing data electronically available in the “thermodynamic database” (TDB) format. This focus is motivated by the fact that it is widely used and can be readily read or imported into most thermodynamic modeling software. This form of data also provides a rather complete thermodynamic description of a given system and thus enables researchers to generate any phase diagram cross-section of interest, a capability typically not available in traditional phase diagram handbooks. For convenience, users can quickly preview selected cross sections directly online. In designing this system, special emphasis was devoted to ensuring that the bibliographic references of the original data sources are transparently reported and to providing links to the original data sources, rather than the data itself, in order to enforce access rights. This effort was made possible by combining and building upon a number of key components, such as the CALPHAD journal's supplementary information section, the NIMS database, the NIST materials data repository, the Crossref bibliographic service, and various thermodynamic (OpenCalphad, ATAT) and graphical (gnuplot, XTK) software.
- Published
- 2018
49. Understanding slow-growing alumina scale mediated by reactive elements: Perspective via local metal-oxygen bonding strength
- Author
-
Brian Gleeson, Yi Wang, Zi Kui Liu, and Shun Li Shang
- Subjects
010302 applied physics ,Bulk modulus ,Materials science ,Scale (ratio) ,Phonon ,Mechanical Engineering ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Oxygen ,Metal ,chemistry ,Mechanics of Materials ,Bonding strength ,visual_art ,0103 physical sciences ,Melting point ,visual_art.visual_art_medium ,Physical chemistry ,General Materials Science ,Bond energy ,0210 nano-technology - Abstract
Interatomic bonding strength/energy can be quantified by stretching force constants (SFC) after first-principles phonon calculations. Here, we show that the slow-growing alumina (α-Al 2 O 3 ) scale mediated by reactive elements (REs) can be understood via the strong RE O bonding energy from the present SFC model applied to oxides (Al 2 O 3 , Cr 2 O 3 , Ti 2 O 3 , ZrO 2 , HfO 2 , Y 2 O 3 , and La 2 O 3 ), Al 3 M, and Al 47 MO 72 (M = Cr, Ti, Zr, Hf, Y, and La). The present model indicates that Hf is the best RE in retarding alumina scale growth, agreeing with the analyses from bulk modulus, melting point, and enthalpy of formation of oxides, and experimental observations.
- Published
- 2018
50. Thermodynamic description of the Ti-Mo-Nb-Ta-Zr system and its implications for phase stability of Ti bio-implant materials
- Author
-
Shun Li Shang, Ji-Cheng Zhao, Cassie Marker, and Zi Kui Liu
- Subjects
010302 applied physics ,Work (thermodynamics) ,Materials science ,General Chemical Engineering ,Thermodynamics ,Titanium alloy ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Computer Science Applications ,Phase (matter) ,0103 physical sciences ,Density functional theory ,Binary system ,0210 nano-technology ,Ternary operation ,CALPHAD ,Phase diagram - Abstract
Titanium alloys are great candidates for applications such as biomedical implants that require biocompatibility, a low Young's modulus and a high strength. However, the properties of Ti alloys are highly dependent on phase stability. In the present work, a database for the Ti-Mo-Nb-Ta-Zr system has been evaluated using the CALPHAD (CALculation of PHAse Diagram) approach. The database was completed by evaluating the accuracy of previously modeled systems from literature and modeling systems that, to the best of the authors’ knowledge, had no modeling available in literature. All of the binary systems that make up the Ti-Mo-Nb-Ta-Zr system had previously modeled thermodynamic descriptions available in the literature and in most cases had multiple different descriptions available, which meant determining which previous thermodynamic description most accurately modeled the binary system with a direct focus on the bcc phase. In order to determine the accuracy of the multiple available thermodynamic descriptions from literature a combination of experimental data (also obtained from the literature) and computed thermochemical properties of the bcc phase from DFT (Density Functional Theory)-based first-principles calculations (present work) were used. Once the thermodynamic descriptions for the binary systems were chosen, focus shifted to the Ti-containing ternary systems. The Ti-Mo-Zr, Ti-Nb-Zr and Ti-Ta-Zr systems had previous thermodynamic description available in literature, which were incorporated without changes into the working database. The Ti-Mo-Ta, Ti-Nb-Ta and Ti-Mo-Nb systems had, to the authors’ knowledge, no descriptions available in the literature. Interaction parameters were determined for the Ti-Mo-Ta and Ti-Nb-Ta systems, and no interaction parameters were introduced for the Ti-Mo-Nb system. The database introduced by this work satisfactorily predicts the thermodynamics of the Ti-Mo-Nb-Ta-Zr system.
- Published
- 2018
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