43 results on '"phase selection"'
Search Results
2. Effects of Oxygen Partial Pressure and Tolerance Factor on Phase Selection of DyMnO3.
- Author
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Kenta Shimomura, Kazuhiko Kuribayashi, Yusaku Seimiya, Suguru Shiratori, and Shumpei Ozawa
- Subjects
PARTIAL pressure ,OXYGEN ,CRYSTAL structure ,MANGANESE ,RARE earth metals ,SOLIDIFICATION - Abstract
The equilibrium crystal structure of LnMnO
3 (Ln: lanthanide) is known to be orthorhombic when larger ions from La3+ to Dy3+ are used as Ln3+ , and hexagonal when smaller ions from Ho3+ to Lu3+ are used. Research indicates that the hexagonal phase forms when the tolerance factor, expressed as functions of radii of the constituent ions, is less than 0.840. In this study, we attempted to induce oxygen deficiency in DyMnO3 through solidification at low oxygen partial pressure using an aerodynamic levitator. The objective was to decrease the tolerance factor by reducing the valence of manganese ions and thereby increasing their ionic radius. The results showed an increase in oxygen deficiency as the oxygen partial pressure decreased. Based on the assumption that the manganese ions' valence decreased due to an increase in oxygen deficiency, the corresponding tolerance factor evaluated from the average ionic radii of manganese and oxygen also decreased. This decrease promoted the formation of the hexagonal phase, similar to the effect observed when the ionic radius of Ln3+ is reduced. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
3. A New Phase Classifier with an Optimized Feature Set in ML-Based Phase Prediction of High-Entropy Alloys.
- Author
-
Zhang, Yifan, Ren, Wei, Wang, Weili, Ding, Shujian, and Li, Nan
- Subjects
FACE centered cubic structure ,MACHINE learning ,ALLOYS ,FEATURE selection ,GENETIC algorithms - Abstract
The phases of high-entropy alloys (HEAs) are closely related to their properties. However, phase prediction bears a significant challenge due to the extensive search space and complex formation mechanisms of HEAs. This study demonstrates a precise and timely methodology for predicting alloy phases. It first developed a machine learning classifier using 145 features and a dataset with 1009 samples to differentiate the four types of alloy phases. Feature selection was performed on the feature set using an Embedded algorithm and a genetic algorithm, resulting in the selection of nine features. The Light GBM algorithm was chosen to train the machine learning model. Finally, the implementation of oversampling and cost-sensitive methods enables LightGBM to tackle the problem of insufficient accuracy in BCC+FCC phase classification. The resulting accuracy of the alloy phase prediction model, evaluated through ten-fold cross-validation, stands at 0.9544. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Analysis on phase selection and microstructure evolution in directionally solidified Zn-Al-Mg-Ce alloy.
- Author
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Ji-peng Li, De-gao Qiao, Shi-wen Dong, Peng Peng, Xian-tao Yan, and Xu-dong Zhang
- Subjects
- *
GALVANIZING , *DIRECTIONAL solidification , *PLATING baths , *ALLOYS , *MICROSTRUCTURE , *EUTECTICS - Abstract
In the process of hot-dip Zn-Al-Mg alloy coating, the plating solution dissipates heat in the direction perpendicular to the steel plate, which is considered to be a process of directional solidification. To understand the relationship between microstructure and cooling rate of Zn-Al-Mg alloys, both the phase constitution and microstructure characteristic length scales of Zn-9.5Al-3Mg-0.01Ce (wt.%) alloy were investigated by the directional solidification experiments at different growth velocities (V=40, 80, 160, 250 µm·s−1). The experimental results show that the microstructure of directionally solidified Zn-9.5Al-3Mg-0.01Ce alloy is composed of primary Al dendrites and (Zn-Al-Mg2Zn11) ternary eutectics at the growth velocities ranging from 40 to 250 µm·s−1. The primary Al dendrites are aligned regularly along the growth direction, accompanied with obvious secondary dendrites. The relationship between the microstructure length scale and the thermal parameters of solidification is obtained: λ1=374.66V−0.383, and λ2=167.5V−0.563 (λ1 is the primary dendrite arm spacing, and λ2 is the secondary dendrit arm spacing). In addition, through the interface response function (IRF) and the nucleation and constitutional undercooling (NCU), the phase selection of Zn-9.5Al-3Mg-0.01Ce is obtained: (Zn+Al+Mg2Zn11) ternary eutectics in the Zn-9.5Al-3Mg-0.01Ce alloy will be replaced by ternary eutectics (Zn+Al+MgZn2) when the growth rate is lower than 7.53 µm·s−1. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. DyMnO3 の相選択に対する雰囲気酸素分圧とトレランス因子 の影響.
- Author
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下村健太, 栗林一彦, 清宮優作, 白鳥 英, and 小澤俊平
- Subjects
NANOINDENTATION tests ,ALUMINUM ,CRYSTAL structure ,PARTIAL pressure ,MANGANESE ,TRANSITION metals - Abstract
The equilibrium crystal structure of LnMnO
3 (Ln: lanthanide) has been reported to be orthorhombic when relatively large ions from La3+ to Dy3+ are used as Ln3+ and hexagonal when relatively small ions from Ho3+ to Lu3+ are used. It has been reported that the hexagonal phase is formed when the tolerance factor, expressed as functions of radii of the constituent ions, is less than 0.840. In the present study, we attempted to induce oxygen deficiency in DyMnO3 under the solidification at low oxygen partial pressure using aerodynamic levitator to reduce the tolerance factor through a decrease in the valence of manganese ions and the accompanying increase in the ionic radius. The results showed that the oxygen deficiency increases with decreasing oxygen partial pressure. Assuming that valence of manganese ions decreased due to the increase in oxygen deficiency, the corresponding tolerance factor evaluated from the average ionic radii of manganese and oxygen decreased, which promoted the formation of the hexagonal phase as is the case with the reduction of the ionic radius of Ln3+ . [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
6. Data-Driven Phase Selection, Property Prediction and Force-Field Development in Multi-Principal Element Alloys
- Author
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Beniwal, Dishant, Jhalak, Ray, Pratik K., Wriggers, Peter, Series Editor, Eberhard, Peter, Series Editor, Verma, Akarsh, editor, Mavinkere Rangappa, Sanjay, editor, Ogata, Shigenobu, editor, and Siengchin, Suchart, editor
- Published
- 2022
- Full Text
- View/download PDF
7. Crystalline or amorphous? A critical evaluation of phenomenological phase selection rules
- Author
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K. Wieczerzak, A. Sharma, C. Hain, and J. Michler
- Subjects
Microstructure ,Thermodynamics ,Multicomponent alloys ,Phase transformations ,Phase selection ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
In this work, we reviewed the available phase selection rules comprising atomic size and topological aspects, entropies, enthalpies, melting points, valence and itinerant electron concentrations, as well as electronegativity, and validated them using a carefully prepared database of CuTiZr alloys, to assess their strengths and weaknesses. Substantially increasing interest over the last two decades in high-entropy alloys and metallic glasses motivated the search for phase selection rules that could support the designing of new alloys. These rules are most often based on phenomenological correlation between structure and topological-, thermodynamic- and/or electronic structure-related properties of alloy systems. The available phase selection criteria are, therefore, not scientifically derived, but rather statistically constructed from available experimental data. Thus, they contain potential pitfalls, hindering the rational interpretation of obtained results. With this in mind, this work discusses the importance of defining the influence of phase transformation kinetics and synthesis method on an alloy’s final structure, while highlighting the challenges of using phenomenological alloying guidelines. Furthermore, we show that the interpretation of available phase selection criteria without caution may lead to the designing and fabrication of alloys with undesired phases.
- Published
- 2023
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- View/download PDF
8. Quantum machine-learning phase prediction of high-entropy alloys.
- Author
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Brown, Payden and Zhuang, Houlong
- Subjects
- *
QUANTUM computers , *MACHINE learning , *SUPERVISED learning , *QUBITS , *OPTIMIZATION algorithms , *QUANTUM superposition - Abstract
[Display omitted] Discovering new high-entropy alloys (HEAs) in the vast compositional space requires a growing power of classical computers for training machine learning models. The exponential increase of HEA data will pose a challenge in making the machine learning process prohibitively time consuming in the foreseeable future. Quantum computers, which use quantum superposition and interference to perform computations, hold great potential in handling big data and accelerating the optimization algorithms ubiquitous in machine learning models. Here we adopt a quantum computer simulator and quantum processors to prepare for the future challenge in new HEA discovery. We first train a classical artificial neural network (ANN), which uses HEAs' compositions as inputs and the corresponding phases as outputs, to predict phase selection. We then apply a quantum computer simulator that implements a hybrid quantum–classical machine learning algorithm to accomplish the same supervised machine learning task. We find that the resulting testing accuracy is comparable to that from classical ANN calculations. We finally apply quantum processors to perform the hybrid quantum–classical machine learning calculations and obtain slightly lower accuracy ascribed to the fragile nature of quantum bits in quantum processors. Our work initiates the adoption of fledgling quantum computers in the noisy intermediate-scale quantum (NISQ) era for discovering new HEAs. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Phase selection and solidification path transition of Ti–48Al–xNb alloys with different cooling rates.
- Author
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He, Tan, Hu, Rui, Yang, Jie-Ren, and Fu, Heng-Zhi
- Abstract
Ti–48Al–xNb alloys were solidified by containerless electromagnetic levitation with quenching system of the conical copper mold. The influence of cooling rates on phase selection of Ti–48Al–xNb alloys was investigated. In near-equilibrium solidification condition, the dendrite β phase is observed as the leading phase. No other metastable phase (e.g., α phase) is observed. In contrast, in rapid solidification condition, the metastable α phase is observed in as-quenched Ti–48Al–2Nb alloy. Furthermore, the metastable α phase is replaced by the primary β phase with Nb addition increasing. For Ti–48Al–(x = 4, 6, 8)Nb alloys, increasing cooling rate results in a solidification path transition. The peritectic reaction (L + β → α) is therefore significantly suppressed. The relationships between primary dendrite arm spacing (λ
1 ) and cooling rate (τ) can be described. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
10. Solvothermal phase selection of Cr3+-doped (NH4)xScF(3+x) compounds (x = 0, 1, 3), structure, and NIR luminescence.
- Author
-
Feng, Sihan, Pan, Zhiyuan, Wang, Yun, Wang, Xuejiao, Zhu, Qi, and Li, Ji-Guang
- Subjects
- *
BLUE light , *SCANDIUM compounds , *LUMINESCENCE , *CRYSTAL structure , *PHOSPHORS - Abstract
[Display omitted] • Efficient and phase-selective synthesis of (NH 4) x (Sc,Cr)F (3+ x) (x = 0, 1, 3) was achieved via methanol-based solvothermal reaction up to 140 °C. • Phase composition was found to critically depend on NH 4 F/(Sc,Cr) molar ratio and reaction temperature. • The vibrational and thermal behaviors of the ammonium fluoroscandates (x = 1, 3) were unveiled. • ScF 3 :Cr3+ showed ∼700–1300 nm NIR luminescence under 470 nm blue light excitation, with a large FWHM of ∼156 nm. 5 at% Cr3+ doped ScF 3 , NH 4 ScF 4 and (NH 4) 3 ScF 6 were selectively synthesized via solvothermal reaction of metal nitrate and NH 4 F in methanol for 24 h, with the effects of NH 4 F/M molar ratio (M=Sc 0.95 Cr 0.05), methanol content and reaction temperature (up to 140 °C) being systematically investigated. The compounds were characterized in detail for crystal structure, microstructure, thermal behavior and vibrational properties, and broadband NIR luminescence (∼700–1300 nm) with an FWHM (full width at half maximum) as large as ∼156 nm was obtained from the as synthesized ScF 3 :Cr3+ phosphor powder under 470 nm blue light excitation. The technique is advantageous over aqueous processing since it allows high yield production of the water-soluble ammonium fluoroscandates and was expected to be well applicable to analogous materials such as those of the Al, Ga and In elements. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Synthesis of CHA zeolite in phenoxide media for CO2 capture.
- Author
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Chen, Yanpeng, Zhu, Rongshu, Chen, Guanyu, Zhao, Minghu, Ju, Min, Cai, Rongming, Gao, Jinqiang, Hong, Mei, and Yang, Shihe
- Subjects
- *
CARBON sequestration , *KINETIC control , *PHENOXIDES , *CHABAZITE , *UNIT cell - Abstract
[Display omitted] • An OSDA-free anion tuning approach to control zeolite polymorphism is reported. • Phenoxide media allow favorable kinetic control to facilitate CHA nucleation. • Stabilized dimeric aluminate intermediate is the key for CHA phase selection. Synthesis of small-pore chabazite (CHA) zeolites in the absence of organic structure-directing agents (OSDA) has been proven difficult. A judicious mixed cation approach recently reported could expand the design space of CHA formation. In a seemingly opposite direction, we herein report an anion tuning approach for controlling the zeolite polymorphism in an OSDA-free system that effectively promotes hierarchical CHA formation in a competitive growth with MER. Phenoxide media, utilizing mild in-situ nucleophilic etching in cooperation with zeolite framework growth, allow beneficial kinetic control to facilitate CHA nucleation. Operando analyses reveal the crucial role of stabilized dimeric aluminate species as a key intermediate for CHA phase selection. The phenol-mediated CHA zeolites exhibit almost perfect 9 molecules per unit cell CO 2 uptake capacity and no CH 4 adsorption. This work offers an anion tuning strategy for controlling zeolite polymorphism as a supplement to the current phase-selection toolbox that utilizes mixed inorganic cations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. A New Phase Classifier with an Optimized Feature Set in ML-Based Phase Prediction of High-Entropy Alloys
- Author
-
Yifan Zhang, Wei Ren, Weili Wang, Shujian Ding, and Nan Li
- Subjects
high-entropy alloy ,machine learning ,data imbalance ,phase selection ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The phases of high-entropy alloys (HEAs) are closely related to their properties. However, phase prediction bears a significant challenge due to the extensive search space and complex formation mechanisms of HEAs. This study demonstrates a precise and timely methodology for predicting alloy phases. It first developed a machine learning classifier using 145 features and a dataset with 1009 samples to differentiate the four types of alloy phases. Feature selection was performed on the feature set using an Embedded algorithm and a genetic algorithm, resulting in the selection of nine features. The Light GBM algorithm was chosen to train the machine learning model. Finally, the implementation of oversampling and cost-sensitive methods enables LightGBM to tackle the problem of insufficient accuracy in BCC+FCC phase classification. The resulting accuracy of the alloy phase prediction model, evaluated through ten-fold cross-validation, stands at 0.9544.
- Published
- 2023
- Full Text
- View/download PDF
13. A 1-ps Bin Size 4.87-ps Resolution FPGA Time-to-Digital Converter Based on Phase Wrapping Sorting and Selection
- Author
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Poki Chen, Joshua Adiel Wijaya, Seiji Kajihara, Trio Adiono, Hsiang-Yu Chen, Ruei-Ting Wang, and Yousuke Miyake
- Subjects
Field programmable gate array (FPGA) ,merged TDL ,phase selection ,phase sorting ,phase wrapping ,time-to-digital converter ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
A field-programmable gate array (FPGA) high-resolution time-to-digital converter (TDC) based on phase-wrapping, sorting, and selection to achieve an extremely fine bin size of 1 ps is proposed in this paper. Based on Nutt interpolation method, a wide measurement range with a high resolution can be realized at the same time. The input signal is fed into tapped delay lines (TDL) with regularized and automated cell placements to generate a multitude of delayed signals with plenty of regularized phase shifts. Due to periodicity, those phase shifts will be equivalently wrapped within a reference clock period and then phase sorting, ROM-based selection are applied to construct a merged TDL with uniform phase division across the reference clock period. The FPGA TDC was implemented successfully on both Altera Stratix IV to achieve a resolution as fine as 1ps with a measurement range of 1s. The short-range integral non-linearity errors (INL) are measured as −1.470– 1.676 LSB for Stratix IV to demonstrate its excellent linearity.
- Published
- 2022
- Full Text
- View/download PDF
14. Observation of Pattern Formation during Electromagnetic Levitation Using High-Speed Thermography.
- Author
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Fang, Yindong, Liu, Dongmei, Zhu, Yongfu, Galenko, Peter K., and Lippmann, Stephanie
- Subjects
THERMOGRAPHY ,LEVITATION ,INFRARED cameras ,PHOTON detectors ,SEMICONDUCTORS - Abstract
Electromagnetic levitation (EML) was employed for studying the velocity and morphology of the solidification front as a function of undercooling of metallic materials. The limitation of the EML technique with respect to low melting alloys that emit outside the visible light spectrum was overcome by employing state-of-the-art high-speed mid-wavelength infrared cameras (MWIR cameras) with a photon detector. Due to the additional thermography contrast provided by the emission contrast of the solid and liquid phases, conductor, and semi-conductor, the pattern formation of Al-based alloys was studied in detail, revealing information on the nucleation, phase selection during solidification, and the influence of convection. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
15. Fault Ride Through of Inverter-Interfaced Renewable Energy Sources for Enhanced Resiliency and Grid Code Compliance.
- Author
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Aboelnaga, Abdallah A., Azzouz, Maher A., Sindi, Hatem F., and Awad, Ahmed S. A.
- Abstract
Inverter-interfaced renewable energy sources (IIRESs) are typically controlled during fault conditions to meet fault ride-through (FRT) requirements, e.g., reactive current generation (RCG) requirements specified by grid codes (GCs). However, fault currents generated by inverters are different from the traditional sources, i.e., synchronous generators. Consequently, phase selection methods (PSMs) used by protection relays could suffer from erroneous fault type classification. This paper develops a dual current controller (DCC) that regulates the inverter's negative- and positive-sequence currents to simultaneously meet phase selection and RCG requirements. First, the negative-sequence-current angle is obtained based on the angles of both zero- and positive-sequence currents to enable a correct operation for phase selection. Then, the positive-sequence current angle is adjusted to reach a trade-off between RCG requirements and phase selection achieved by the negative-sequence current. Lastly, the reference currents of the IIRES are generated in the stationary frame without violating the inverter's current limits. The proposed DCC supports the grid voltage by meeting the RCG requirements and enhancing the grid reliability and resilience by enabling correct phase selection. Comprehensive time-domain and real-time simulation verify the precise operation of the proposed DCC under various fault conditions and GCs. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
16. Analysis on phase selection and microstructure evolution in directionally solidified Zn-Al-Mg-Ce alloy
- Author
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Li, Ji-peng, Qiao, De-gao, Dong, Shi-wen, Peng, Peng, Yan, Xian-tao, and Zhang, Xu-dong
- Published
- 2023
- Full Text
- View/download PDF
17. Detection of Damaged Phases and Determination of the Place of Damage of an Electrical Transmission Line with One-Sided Observation.
- Author
-
Kochetov, I. D., Lyamets, Yu. Ya., and Maslov, A. N.
- Abstract
The tasks of phase selection (recognition of damaged phases) and location (determination of the fault location) are solved by a universal algorithm for monitoring an arbitrary site of the presumed fault location. The currents and voltages observed on one side are converted into estimates of the electrical quantities at that location, which are determined on the assumption that the line is not damaged before that position. The converter is an algorithmic model of the initial section of the line with variable length. The algorithmic model is created based on a priori information about the line parameters. Information about the structure and parameters of the rest of the network is required to determine a priori coordinate functions that express the currents in the damage branches through the components of the output voltages or currents of the algorithmic model. The type of components is determined by the completeness of the observer's information base. The most valuable emergency components in terms of information are available, when a short circuit (SC) occurs against the background of the previous mode. However, in the situation when voltage is applied to an already damaged line, then one must be satisfied with the components of the zero and negative sequences. The null value of the reactive power of all damaged phases serve as the criterion for determination of the fault location (DFL), and the boundary conditions for single- and two-phase short circuits as the criterion for phase selection. The tasks of selection and location are closely intertwined. Generally speaking, a complete information base provides an opportunity to perform the detection and ranging without regard to the type of short circuit. But this will be a preliminary estimate of the location of the short circuit. Recognition of damaged phases will result in its refinement. But with an incomplete information base, phase selection certainly precedes location. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Triple Current Control of Four-Wire Inverter-Interfaced DGs for Correct Fault Type Identification.
- Author
-
Medhat, Wael and Azzouz, Maher A.
- Abstract
Inverter-interfaced distributed generators (IIDGs) have fault current signatures that could jeopardize protective relaying. This paper unveils the failure of phase selection methods (PSMs) utilized by commercial relays in the presence of four-wire IIDGs, which adversely impacts the grid resiliency and reliability. A triple current controller (TCC) is proposed to regulate the inverter’s sequence currents during unbalanced faults to ensure accurate fault type identification. The negative- and positive-sequence components are extracted using a decoupled double synchronous reference frame (DDSRF)-based phase-locked loop (PLL). Further, a second-order generalized integrator (SOGI)-based PLL is employed for zero-sequence component synchronization. The negative- and zero-sequence reference currents are generated to force the angles of IIDG sequence currents to behave like those from synchronous generators (SGs) and abide by the inverter’s current limits. Consequently, commercial PSMs can correctly identify the fault type. The proposed TCC scheme pertains to four-wire as well as transformer-less IIDGs. A performance evaluation using time-domain simulations is conducted on a CIGRE benchmark system to confirm the success of the proposed control scheme under different fault conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
19. Investigation of Heat Transfer of Bulk and Thin-Film PbInTe Samples by the Method of Dynamic Gratings.
- Author
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Ivakin, E. V., Tolstik, A. L., Gorbach, D. V., and Stankevich, A. A.
- Subjects
- *
HEAT transfer , *THERMAL diffusivity , *HOLOGRAPHIC gratings , *LASER beams , *PULSED lasers , *SAMPLING methods , *THIN films - Abstract
Measurements of the thermal diffusivity of thin and bulk indium-doped lead telluride have been taken using a modified method of dynamic gratings. Thermal gratings were recorded by a 20 ns pulsed laser radiation at a wave length of 532 nm. Dynamic gratings were recorded by a 635 nm continuous laser radiation. The analysis of the diffraction signal kinetics made it possible to determine the life-time of thermal gratings recorded in the investigated samples. It is shown that the use of an additional homodyne field coherent with respect to the diffraction signal field makes it possible to enhance and filter off the selected information component. Based on registered kinetic dependences of the diffracted signal intensity, the thermal diffusivity of bulk and thin film indium-doped lead telluride samples was determined. It has been established that for a micron-thick film, the thermal diffusivity is ten percent lower than for a bulk sample. An investigation has been made into the dependence of the heat transfer in the said samples on their temperature and it has been shown that the rise in the samples′ temperature in the range from 40 to 95°C results in a 20-percent decrease of their thermal diffusivity. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
20. Phase selection and microstructure evolution within eutectic Ti-Si alloy solidified at containerless state.
- Author
-
Luo, ZhiCong, Chang, Jian, and Wang, HaiPeng
- Abstract
Phase selection and microstructure evolution of the undercooled eutectic Ti-Si alloy were systematically investigated by the electromagnetic levitation method, and the maximum undercooling achieved was 318 K (0.2T
E ). The migration of the liquid-solid interface was in-situ detected by a high-speed camera system. When the undercooling is smaller than 140 K, the liquid-solid interface is smooth. Once the undercooling arrives at 230 K, the liquid-solid interface is irregular, which reflects the growth transition from the solute control to the combined controls of solute and thermal. The eutectic growth velocity increases as an exponential function of undercooling. The electromagnetic stirring effect makes it difficult to increase undercooling, but plays an important role in accelerating the eutectic reaction velocity at low and moderate undercoolings. Primary dendritic β-Ti phase appears in the solidified alloy from 63 to 176 K undercoolings, and the microstructure is completely composed of eutectic once the undercoolings increase up to 230 K. When the undercoolings exceed 273 K, the microstructure consists of uniformly distributed irregular eutectic. For the drop tube experiments, the microstructures composed of a large amount of dendritic α-Ti phase and eutectic phase are found in a wide range of diameters from 69 to 725 µm. As the decrease of diameter, the solubility of Si in the dendritic α-Ti phase dramatically increases from 6.80% to 10.73%, and the ratio of the area occupied by the dendritic α-Ti on a cross-section of solidified alloy obviously increases from 23.52% to 41.02%, which result from the combined effects of high undercooling and large cooling rate. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
21. 考虑光伏选相投切的低压配电网三相平衡优化.
- Author
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陈家超, 李钦豪, 唐 渊, and 张勇军
- Subjects
ELECTRICAL load ,LAPLACIAN matrices ,POWER resources ,ENERGY storage ,REACTIVE power - Abstract
Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
22. 配电网单相接地故障柔性自适应消弧新方法 .
- Author
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游建章, 郭谋发, 蔡文强, and 高 伟
- Subjects
ELECTRIC potential ,POWER resources ,VOLTAGE control ,VOLTAGE ,PROBLEM solving ,VACUUM arcs ,FAULT currents - Abstract
Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
23. Room Temperature Ion Beam Synthesis of Ultra-Fine Molybdenum Carbide Nanoparticles: Toward a Scalable Fabrication Route for Earth-Abundant Electrodes.
- Author
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Fiedler H, Malone N, Mitchell DRG, Nancarrow M, Jovic V, Waterhouse GIN, Kennedy J, and Gupta P
- Abstract
Molybdenum carbides are promising low-cost electrocatalysts for electrolyzers, fuel cells, and batteries. However, synthesis of ultrafine, phase-pure carbide nanoparticles (diameter < 5 nm) with large surface areas remains challenging due to uncontrollable agglomeration that occurs during traditional high temperature syntheses. This work presents a scalable, physical approach to synthesize molybdenum carbide nanoparticles at room temperature by ion implantation. By tuning the implantation conditions, various molybdenum carbide phases, stoichiometries, and nanoparticle sizes can be accessed. For instance, molybdenum ion implantation into glassy carbon at 30 keV energy and to a fluence of 9 × 10
16 at cm-2 yields a surface η-Mo3 C2 with a particle diameter of (10 ± 1) nm. Molybdenum implantation into glassy carbon at 60 keV to a fluence of 6 × 1016 at cm-2 yields a buried layer of ultrafine γ'-MoC/η-MoC nanoparticles. Carbon ion implantation at 20 keV into a molybdenum thin film produces a 40 nm thick layer primarily composed of β-Mo2 C. The formation of nanoparticles in each molybdenum carbide phase is explained based on the Mo-C phase diagram and Monte-Carlo simulations of ion-solid interactions invoking the thermal spike model. The approaches presented are widely applicable for synthesis of other transition metal carbide nanoparticles as well., (© 2023 Wiley‐VCH GmbH.)- Published
- 2024
- Full Text
- View/download PDF
24. Observation of Pattern Formation during Electromagnetic Levitation Using High-Speed Thermography
- Author
-
Yindong Fang, Dongmei Liu, Yongfu Zhu, Peter K. Galenko, and Stephanie Lippmann
- Subjects
electromagnetic levitation ,phase transformation ,in-situ observation ,phase selection ,Crystallography ,QD901-999 - Abstract
Electromagnetic levitation (EML) was employed for studying the velocity and morphology of the solidification front as a function of undercooling of metallic materials. The limitation of the EML technique with respect to low melting alloys that emit outside the visible light spectrum was overcome by employing state-of-the-art high-speed mid-wavelength infrared cameras (MWIR cameras) with a photon detector. Due to the additional thermography contrast provided by the emission contrast of the solid and liquid phases, conductor, and semi-conductor, the pattern formation of Al-based alloys was studied in detail, revealing information on the nucleation, phase selection during solidification, and the influence of convection.
- Published
- 2022
- Full Text
- View/download PDF
25. Phase Selection and Microhardness of Directionally Solidified AlCoCrFeNi2.1 Eutectic High-Entropy Alloy
- Author
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Peng, Peng, Li, Shengyuan, Chen, Weiqi, Xu, Yuanli, Zhang, Xudong, Ma, Zhikun, and Wang, Jiatai
- Published
- 2022
- Full Text
- View/download PDF
26. Phase Selection Rules of Multi-Principal Element Alloys.
- Author
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Wang L and Ouyang B
- Abstract
Computational prediction of phase stability of multi-principal element alloys (MPEAs) holds a lot of promise for rapid exploration of the enormous design space and autonomous discovery of superior structural and functional properties. Regardless of many plausible works that rely on phenomenological theory and machine learning, precise prediction is still limited by insufficient data and the lack of interpretability of some machine learning algorithms, e.g., convolutional neural network. In this work, a comprehensive approach is presented, encompassing the development of a complete dataset that contains 72 387 density functional theory calculations, as well as a predictive global phenomenological descriptor. The phase selection descriptor, based on atomic electronegativity and valence electron concentration, significantly outperforms the widely used valence electron concentration, excelling in both accuracy (with an f1 score of 63% compared to 47%) and its ability to predict the HCP phase (0.48 recall compared to 0). The comprehensive data mining on the global design space of 61 425 quaternary MPEAs made from 28 possible metals, together with the phenomenological theory and physical interpretation, will set up a solid computational science foundation for data-driven exploration of MPEAs., (© 2024 Wiley‐VCH GmbH.)
- Published
- 2024
- Full Text
- View/download PDF
27. The effect of nanometre-scale kinetic competition on the phase selection in Zr/Si superstructure.
- Author
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Cao, Guoqin, Guo, Min, Yang, Feifan, Xu, Hongjie, Shao, Guosheng, and Hu, Junhua
- Subjects
- *
ATOMIC structure , *NUCLEAR reactor cores , *NUCLEAR reactor accidents , *MOLECULAR dynamics , *PASSIVATION - Abstract
Nano structured coating system demonstrates outstanding performance stemming from unique structure evolution. Zr/Si coating was proposed as an ideal candidate for the protection of Zr alloy cladding. However, the phase selection remains a challenge to coordinate the complex requirement under the service and accident conditions of reactor core. In this work, a phase selection mechanism for amorphous Zr-Si-O (abbr. ZSO) was elucidated by the competitive consumption of Zr layer by silicidation and oxidation, which was also scale-dependent. The energy-loss near-edge fine structure and nanoindentation were also employed to characterize the unique scale effect in the two processes. Both the oxides kinetics and elastic modulus gain indicated an immediate passivation process under the subcritical condition after the in situ phase selection of the amorphous ZSO. Ab initio molecular dynamics (AIMD) was performed to disclose the origination of depressed O migration in ZSO. The multilayer structure also shows accident tolerance potential. The interfacial phase selection provided a strategy to regulate mesoscale structure originating from nanomter interface and meets the diversified requirement for "structure-performance relationship" under the service and accident conditions. • Nano Zr-Si-O (ZSO) layer was in situ formed on the interface of Zr/Si. • The phase selection of ZSO was ascribed to the competition between silicidation and oxidation. • The superior oxidation resistance of multilayer was attributed to the formation of ZSO. • The strong bonding and compact atomic structure in ZSO was revealed by experiment and modeling. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. EVOLVE: Learning volume-adaptive phases for fast 3D magnetic resonance scan and image reconstruction.
- Author
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Liu, Yiming, Pang, Yanwei, Sun, Xuebin, Hou, Yonghong, and Xu, Hui
- Subjects
- *
MAGNETIC resonance imaging , *HIGH resolution imaging , *THREE-dimensional imaging , *PHASE coding - Abstract
Compared with 2D Magnetic Resonance Imaging (MRI), 3D MRI is more powerful for generating high resolution images and visualizing small anatomical structures. However, 3D MRI acquisition is much more time-consuming due to the significantly larger number of phase encoding steps, which is directly proportional to the acquisition time. This paper proposes to select a volume-adaptive small subset of phases to accelerate 3D MRI scans and accurately reconstruct 3D images from the corresponding undersampled 3D k-space data. To avoid the delays caused by computationally expensive yet high-performance volume-adaptive phase selection, we propose a strategy of selecting multiple phases based on sampled slices from the volume during idle time within the repetition time (TR). To enhance the performance of phase selection, we propose a novel three-directional cross-attention phase selection network. Additionally, to improve the reconstruction performance, we introduce a three-directional slice-wise volume reconstruction. To the best of our knowledge, the proposed method, which we called EVOLVE (l e arning vol ume-adapti ve phases), is the first work that learns volume-adaptive phases for fast 3D MRI. The extensive experimental results on a large-scale 3D MRI dataset at various acceleration factors demonstrate the substantial performance improvement in terms of image reconstruction achieved by using the EVOLVE method for phase selection compared to traditional learning free 3D MRI phase selection methods. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
29. Adaptive Current-Angle-Based Phase Selection for Microgrids With Inverter-Interfaced Renewable Energy Sources
- Author
-
Maher A. Azzouz and Abdallah A. Aboelnaga
- Subjects
Phase selection ,General Computer Science ,business.industry ,Computer science ,020209 energy ,0202 electrical engineering, electronic engineering, information engineering ,Electrical engineering ,Inverter ,020206 networking & telecommunications ,02 engineering and technology ,Current (fluid) ,business ,Renewable energy - Published
- 2022
- Full Text
- View/download PDF
30. Selective Phase Tripping for Microgrids Powered by Synchronverter-Interfaced Renewable Energy Sources
- Author
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Ehab F. El-Saadany, Maher A. Azzouz, and Hatem H. Zeineldin
- Subjects
Phase selection ,Computer science ,business.industry ,020209 energy ,Phase (waves) ,Energy Engineering and Power Technology ,02 engineering and technology ,Fault (power engineering) ,Inrush current ,Renewable energy ,Control theory ,Tripping ,Limit (music) ,0202 electrical engineering, electronic engineering, information engineering ,Limiter ,Electrical and Electronic Engineering ,business - Abstract
Synchronverters are inverters that imitate the behavior of synchronous generators to enhance the dynamics of renewable energy sources (RESs) powering microgrids. However, the synchronverter's inrush currents during faults could reach intolerable levels. Limiting the synchronvertery's fault currents could obstruct protection relays from identifying faulted phase(s) during unbalanced faults, and hence, jeopardizing selective phase tripping (SPT). This paper unveils the root causes behind the deviation in phase selection that hinder SPT in microgrids powered by synchronverters. Virtual-impedance fault current limiters (VI-FCLs) are proposed for synchronverters to ensure accurate SPT by commercial relays and limit their sequence and DC inrush currents. Based on a short-circuit analysis, the positive- and negative-sequence VI-FCLs, as well as the active-to-reactive power ratio of synchronverters, are regulated to enable SPT and protect synchronverters from inrush currents. Simulation results using PSCAD/EMTDC ensure the effectiveness of the proposed control scheme in enabling reliable SPT in microgrids with synchronverters. The efficacy of the proposed scheme is assured by examining various fault types, a wide range of fault resistances, and the grid-connected and islanded modes.
- Published
- 2021
- Full Text
- View/download PDF
31. Duplex corrosion mechanisms correlated to α/γ phase selection in containerlessly processed Fe-Cr-Ni-Mo alloy.
- Author
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Li, L.Y., Sun, C.H., Ruan, Y., and Wei, B.
- Subjects
- *
ALLOYS , *PITTING corrosion , *CORROSION potential , *CORROSION in alloys , *CORROSION resistance , *DUPLEX stainless steel , *STAINLESS steel - Abstract
The α/γ phase selection mechanism and corrosion resistance of Fe-21%Cr-12%Ni-5%Mo alloy were investigated by both individual electromagnetic levitation (EML) and EML coupled with falling quench (EML+FQ) techniques. The decomposition of primary δ phase could be partially or completely suppressed in two containerless processing. Both selective and pitting corrosion behaviors were discovered in alloy, which were related to the crystalline orientations and solute distributions of constituent phases. The anti-corrosion property of EML+FQ processed alloy was significantly enhanced with higher corrosion potential of 0 V SCE , lower corrosion current density of 4.1 × 10−7 A/cm2 and lower corrosion rate decreasing over one order of magnitude. [Display omitted] • Multiple containerless processing method was proposed to improve the undercooling and cooling rate of alloy. • The decomposition of primary δ phase could be partially or completely suppressed in two containerless processing. • Corrosion behaviors of alloy were related to the crystalline orientations and solute distributions of constituent phases. • he in-situ observation of alloy corrosion process indicated different corrosion rate in two containerless processing. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Instantaneous incremental current-based faulted phase selection algorithm.
- Author
-
Wijekoon, Jagannath and Rajapakse, Athula D.
- Subjects
- *
FAULT location (Engineering) , *ALGORITHMS , *ANGLES , *TRANSDUCERS , *BANDWIDTHS - Abstract
• A faulted phase selection method using locally measured instantaneous incremental currents. • Enhances the relay operating time and enable single-pole tripping schemes. • Does not need a communication channel or voltage transducers. • can be implemented in systems with low sampling rates and avoids the need to use transducers with high bandwidth. • Applicable to a wide range of line lengths, almost independent of fault resistance and not affected fault inception angle and require only three threshold settings. A novel, simple and fast method to identify the faulted phases using the maximum rate of change of incremental current (ROCOIC) is proposed. Six indices are calculated considering a pairwise comparison of ROCOIC. The decision-making process is based on selecting which two indices are the largest among all. The algorithm requires only three thresholds to detect fault inception and to identify the ground and three-phase faults. Simulation studies show that the method is robust and not affected by fault inception angle, fault location, and fault resistance. The proposed method only requires locally measured current signals. Since the method relies on the fundamental component of instantaneous incremental current, the proposed method can be implemented in systems with low sampling rates and avoids the need to use transducers with high bandwidth. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. A Many-Objective Evolutionary Algorithm Based on Two-Phase Selection
- Author
-
Wei Li-sen and Li Er-chao
- Subjects
Mathematical optimization ,Phase selection ,Computer science ,Evolutionary algorithm ,General Medicine - Abstract
Aims: The main purpose of this paper is to achieve good convergence and distribution in different Pareto fronts. Background: Research in recent decades has shown that evolutionary multi-objective optimization can effectively solve multi-objective optimization problems with no more than 3 targets. However, when solving MaOPs, the traditional evolutionary multi-objective optimization algorithm is difficult to effectively balance convergence and diversity. In order to solve these problems, many algorithms have emerged, which can be roughly divided into the following three types: decomposition-based, indexbased, and dominance relationship-based. In addition, there are many algorithms that introduce the idea of clustering into the environment. However, there are some disadvantages to solving different types of MaOPs. In order to take advantage of the above algorithms, this paper proposes a manyobjective optimization algorithm based on two-phase evolutionary selection. Objective: In order to verify the comprehensive performance of the algorithm on the testing problem of different Pareto front, 18 examples of regular PF problems and irregular PF problems are used to test the performance of the algorithm proposed in this paper. Method: This paper proposes a two-phase evolutionary selection strategy. The evolution process is divided into two phases to select individuals with good quality. In the first phase, the convergence area is constructed by indicators to accelerate the convergence of the algorithm. In the second phase, the parallel distance is used to map the individuals to the hyperplane, and the individuals are clustered according to the distance on the hyperplane, and then the smallest fitness in each category is selected. Result: For regular Pareto front testing problems, MaOEA/TPS performed better than RVEA, PREA, CAMOEA and One by one EA in 19, 21, 30, 26 cases, respectively, while it was only outperformed by RVEA, PREA, CAMOEA and One by one EA in 8, 5, 1, and 6 cases. For the irregular front testing problem, MaOEA/TPS performed better than RVEA, PREA, CAMOEA and One by one EA in 20, 17, 25, and 21 cases, respectively, while it was only outperformed by RVEA, PREA, CAMOEA and One by one EA in 6, 8, 1, and 6 cases. Conclusion: The paper proposes a many-objective evolutionary algorithm based on two phase selection, termed MaOEA/TPS, for solving MaOPs with different shapes of Pareto fronts. The results show that MaOEA/TPS has quite a competitive performance compared with the several algorithms on most test problems. Other: Although the algorithm in this paper has achieved good results, the optimization problem in the real environment is more difficult, therefore, applying the algorithm proposed in this paper to real problems will be the next research direction.
- Published
- 2022
- Full Text
- View/download PDF
34. Crystalline or amorphous? A critical evaluation of phenomenological phase selection rules.
- Author
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Wieczerzak, K., Sharma, A., Hain, C., and Michler, J.
- Subjects
- *
METALLIC glasses , *MELTING points , *ALLOYS , *ATOMIC radius , *PHASE transitions , *SEMIMETALS - Abstract
[Display omitted] • Phase selection rules available in the literature were reviewed and validated using the carefully prepared alloy database. • The importance of the kinetics of phase transitions in the interpretation of phase selection models is discussed. • The importance of synthesis method in the interpretation of phase selection models is discussed. • The strengths and weaknesses of each of the phase selection models have been identified. In this work, we reviewed the available phase selection rules comprising atomic size and topological aspects, entropies, enthalpies, melting points, valence and itinerant electron concentrations, as well as electronegativity, and validated them using a carefully prepared database of CuTiZr alloys, to assess their strengths and weaknesses. Substantially increasing interest over the last two decades in high-entropy alloys and metallic glasses motivated the search for phase selection rules that could support the designing of new alloys. These rules are most often based on phenomenological correlation between structure and topological-, thermodynamic- and/or electronic structure-related properties of alloy systems. The available phase selection criteria are, therefore, not scientifically derived, but rather statistically constructed from available experimental data. Thus, they contain potential pitfalls, hindering the rational interpretation of obtained results. With this in mind, this work discusses the importance of defining the influence of phase transformation kinetics and synthesis method on an alloy's final structure, while highlighting the challenges of using phenomenological alloying guidelines. Furthermore, we show that the interpretation of available phase selection criteria without caution may lead to the designing and fabrication of alloys with undesired phases. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
35. Al-Ce-Mn Solidification Phase Selection and Solid-State Phase Transformations
- Author
-
Sisco, Kevin Dean
- Subjects
- Additive Manufacturing, Phase Selection, Al-Ce-Mn, Phase Transformations, Non-Equilibirum, Metallurgy
- Abstract
The design of Al alloys has become an important topic in Additive Manufacturing (AM). The adoption of Al alloys to AM has been difficult because traditional alloys are prone to processing related defects such as solidification cracking. The Al-10Si-Mg alloy was initially adopted because of its resistance to solidification cracking. However, the Al-10Si-Mg alloy has reduced tensile properties especially at high temperatures, where the silicon phase coarsens readily. Therefore, efforts have been made to design new Al alloys that can take advantage of the AM processing. The goal of new alloys is to optimize based on rapid solidification conditions, while being less prone to processing related defects. The Al-Ce, and higher order Al-Ce-X, systems have been adopted because of the low solubility and diffusivity of Ce through FCC Al. The challenge is metastable phases form as a function of the unique processing conditions. Metastable phases have been observed to have unique phase transformations during heat treatment. The goal is to understand the above observations. In this work, an Al-10Ce-8Mn (wt.%) alloy is used to understand the metastable phase Al20Mn2Ce. The Al20Mn2Ce phase, surrounded by FCC Al has different decomposition pathways (at 400 C) depending on its thermal history within a single weld track. Initially, the research focuses on an AM Al-Ce-Mn part that demonstrates the change in decomposition pathways based upon the local solidification conditions, e.g., primary Al20Mn2Ce to eutectic (between FCC Al and Al20Mn2Ce) solidification. Following the AM parts, weld tracks are preformed to understand the role of solidification conditions that can lead to each decomposition pathway observed in the Al-Ce-Mn system. The interface response function model is used to understand phase selection as a function of solidification conditions. The overall goal of this work is to demonstrate how a single metastable phase in a weld track, specifically Al20Mn2Ce, may be manipulated by local solidification conditions, and how that affects the subsequent phase decomposition. The impact of this work is to understand the role of solidification conditions on the solid-state phase transformation to give insight into how the mechanical properties of a particular alloy can be controlled.
- Published
- 2023
36. Prediction of phase selection of amorphous alloys and high entropy alloys by artificial neural network.
- Author
-
Wang, Lin, Li, Peiyou, Zhang, Wei, Wan, Fangyi, Wu, Junxia, Yong, Longquan, and Liu, Xiaodi
- Subjects
- *
INTERMETALLIC compounds , *ENTROPY , *ATOMIC radius , *AMORPHOUS alloys , *ALLOYS - Abstract
To avoid the lack of unified physical significance of the random combination of characteristic parameters, four characteristic parameters with potential energy distribution were selected to predict the phase selection of three type of amorphous alloys (AM), solid solution alloys (SS) and high entropy alloys containing intermetallic compounds (IM) by artificial neural network (ANN) in machine learning. To improve the prediction accuracy, the combination of three different parameters can be used to predict the phase of AM and IM alloys, and the combination of four different parameters can be used to predict the phase of SS alloys. The mean square error (MSE) describes the error between the real value and the predicted value, which directly affects the prediction accuracy. For the AM and IM alloys, the partial three parameter combinations with the lowest MSE values have highest prediction accuracy, for SS alloys, the four parameter combination with the lowest MSE value has highest prediction accuracy. The correlation coefficient (R) is used to evaluate the fitting effect of the model. Based on the correspondence between the R values and the prediction accuracy, it can be concluded that the current ANN model is accurate in predicting the phase selection of three type of alloys, and is the good learning model. The sensitivity matrix (S) calculated according to the weight (w) is an important parameter that affects the prediction accuracy. The S values of the atomic size difference (δ) have a greater impact on the phases of AM, SS and IM alloys; however, the corresponding S values of mixing enthalpy (Δ H m) in the AM and SS alloys have the weak influence. [Display omitted] • Four parameters were selected to predict phases of three types alloys. • Three parameter combination were used to predict phases of AM and IM alloys. • For AM and IM alloys, partial three parameter combinations have highest prediction accuracy. • Current ANN model is accurate in predicting phases of three type of alloys. To avoid the lack of unified physical significance of the random combination of characteristic parameters, and to solve the problem that there are many factors influencing the phase selection by multiple parameters, four characteristic parameters with potential energy distribution were selected to predict the phase selection of three type of amorphous alloys (AM), solid solution alloys (SS) and high entropy alloys containing intermetallic compounds (IM) by artificial neural network (ANN) in machine learning. To improve the prediction accuracy, the combination of three different parameters can be used to predict the phase of AM and IM alloys, and the combination of four different parameters can be used to predict the phase of SS alloys. For the AM and IM alloys, the partial three parameter combinations with the lowest mean square error (MSE) values have highest prediction accuracy, for SS alloys, the four parameter combination with the lowest MSE value has highest prediction accuracy. Based on the correspondence between the correlation coefficient (R) values and the prediction accuracy, it can be concluded that the current ANN model is accurate in predicting the phase selection of three type of alloys, and is the good learning model. The sensitivity matrix (S) values indicate that the atomic size difference (δ) have a greater impact on the phases of AM, SS and IM alloys; however, the corresponding S values of mixing enthalpy (Δ H m) in the AM and SS alloys have the weak influence. The current learning model and the combination of three or four characteristic parameters can predict the AM and SS phase varified by X-ray diffraction of new Ti-Cu-Ni-Zr (AM) and Fe-Co-Ni-Cu-Ti (SS) alloys, thus accelerating the composition design and phase composition selection of new alloys. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. A kinetic transition from peritectic crystallization to amorphous solidification of rapidly quenched refractory Nb-Ni alloy.
- Author
-
Zhao, J.F., Li, M.X., Wang, H.P., and Wei, B.
- Subjects
- *
GLASS transition temperature , *ISOTHERMAL transformation diagrams , *CRYSTALLIZATION , *SOLIDIFICATION , *INTERMETALLIC compounds , *DISCONTINUOUS precipitation , *ALLOYS , *AMORPHOUS alloys - Abstract
In this study, the kinetic transition of solidification modes for refractory peritectic Nb 54 Ni 46 alloy was revealed using melting spinning experiments combined with molecular dynamics (MD) simulation and classical nucleation theory. This begins with a shift from the usual peritectic solidification to the direct precipitation of the peritectic Nb 7 Ni 6 phase when the roller speed reaches 10 m/s. Once the roller speed exceeds 20 m/s, the nucleation of the Nb 7 Ni 6 phase is suppressed and the amorphous phase forms. The high-resolution transmission electron microscopy images indicate that the stacking fault and twining model of the peritectic Nb 7 Ni 6 phase are {10 1 ¯ 2}/< 1 ¯ 011> with a misorientation angle of 35.65°. The results of an individual local crystallization zone in amorphous matrix imply that the chemically disordered crystalline structure is more likely to form during the early stages of nucleation and growth, whereas the chemically ordered crystalline structure may evolve during the growth of the complex intermetallic compound Nb 7 Ni 6 phase. Furthermore, the MD simulation of the glass transition temperature agrees well with the experiment, and the Voronoi polyhedron analysis suggests that the Ni-centered 〈0,0,12,0〉, 〈0,2,8,2〉 as well as Nb-centered 〈0,1,10,4〉 icosahedron-like clusters and their medium-range ordered structures play an important role in the formation of amorphous Nb 54 Ni 46 alloy. In addition, the predictions made using classical nucleation theory and the time-temperature-transformation diagram propose that the phase selection rules are consistent with the experimental results as the undercooling and cooling rate increase, with the critical cooling rate for the formation of amorphous phase determined to be 1.71 × 107 K/s. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. Re-Examination of the Microstructural Evolution in Undercooled Co-18.5at.%B Eutectic Alloy
- Author
-
Yixuan He, Yuhao Wu, Fan Bu, Yiyuan Zhang, Yifan Zhang, Bo Hei, Jianbao Zhang, and Haifeng Wang
- Subjects
solidification pathway ,Co–B system ,phase selection ,pseudoeutectic regions ,recalescence degree ,General Materials Science - Abstract
The undercooling (∆T) dependencies of the solidification pathways, microstructural evolution, and recalescence behaviors of undercooled Co-18.5at.%B eutectic alloys were systematically explored. Up to four possible solidification pathways were identified: (1) A lamellar eutectic structure consisting of the FCC–Co and Co3B phase forms, with extremely low ΔT; (2) The FCC–Co phase primarily forms, followed by the eutectic growth of the FCC–Co and Co2B phases when ΔT < 100 K; (3) As the ΔT increases further, the FCC–Co phase primarily forms, followed by the metastable Co23B6 phase with the trace of an FCC–Co and Co23B6 eutectic; (4) When the ΔT increases to 277 K, the FCC–Co phase primarily forms, followed by an FCC–Co and Co3B eutectic, which is similar in composition to the microstructure formed with low ΔT. The mechanisms of the microstructural evolution and the phase selection are interpreted on the basis of the composition segregation, the skewed coupled zone, the strain-induced transformation, and the solute trapping. Moreover, the prenucleation of the primary FCC–Co phase was also detected from an analysis of the different recalescence behaviors. The present work not only enriches our knowledge about the phase selection behavior in the undercooled Co–B system, but also provides us with guidance for controlling the microstructures and properties practically.
- Published
- 2022
- Full Text
- View/download PDF
39. Compensated phase selection method based on virtual magnitude rezoning for transmission lines emanating from wind farms.
- Author
-
Li, Xu, Lu, Yuping, Jiang, Wentao, and Qin, Jiaqi
- Subjects
- *
ELECTRIC lines , *STREAM channelization , *SYNCHRONOUS generators , *FAULT zones , *FAULT currents , *WIND power plants , *OFFSHORE wind power plants - Abstract
• The compensated PSM proposed in this paper does not need the zero-sequence current as an angle comparison reference. • The virtual magnitude factor-assisted rezoning principle enables the compensated PSM to successfully identify the faulty phase(s) under different fault conditions. • The compensated PSM does not necessitate a high-bandwidth communication channel and additional improvements in wind generators' control strategies. The current angle-based phase selection method (PSM) determines the specific faulty phase(s) based on the relative angles of the superimposed sequence currents at the fault point under different fault types. However, by contrast with synchronous generators (SGs), the superimposed sequence impedances of wind generators present significantly different fault features, which may deprive the unified phase angle property shown in the fault component network, and consequently accompanied by the angle offset between the respective superimposed sequence currents at the relay location and the fault point. In the meantime, the weak-infeed characteristics of the wind farm may weaken the fault signature of the current quantities. As a result, the performance of current angle-based PSM may deteriorate when applied to lines emanating from wind farms. To address these problems, this paper firstly introduces the voltage information to compensate the superimposed sequence currents such that enabling the current angle relationship to be reflected accurately at the relay location. Furthermore, to eliminate the possibility that the current angle-based PSM may provide misleading indications of faulty phase(s) under particular scenarios as it solely depends on the angle comparison, the virtual magnitude factor is constructed and utilized to optimize the fault type zones in the complex plane. Compared with the existing current angle-based PSM, some salient merits of the compensated PSM based on virtual magnitude rezoning are its immunity to the weak-infeed level, independence from wind farms' operating status, and strong tolerance capability against fault resistance. Extensive simulation results under different fault conditions show the expected performance of the proposed PSM. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
40. Phase selection and characterization of Fe-based multi-component amorphous composite.
- Author
-
Zhang, P.C. and Wang, H.P.
- Subjects
- *
SOLIDIFICATION , *HARDNESS - Published
- 2022
- Full Text
- View/download PDF
41. Phase selection and mechanical properties of directionally solidified AlCoCrFeNi2.1 eutectic high-entropy alloy.
- Author
-
Peng, Peng, Li, Shengyuan, Chen, Weiqi, Xu, Yuanli, Zhang, Xudong, Ma, Zhikun, and Wang, Jiatai
- Subjects
- *
EUTECTIC structure , *DIRECTIONAL solidification , *CRITICAL velocity , *INDUSTRIAL capacity , *TENSILE tests , *EUTECTIC alloys - Abstract
• Full lamellar eutectic is obtained in hypoeutectic directionally solidified HEAs. • Critical velocity for transition of leading phase is calculated by using IRF. • Relationship between the microstructure and mechanical properties is clarified. Recent studies report that eutectic high entropy alloys (EHEA) which possess both high strength and high ductility have potential industrial applications. In the present work, the solidification behaviors and mechanical properties of directionally solidified AlCoCrFeNi 2.1 EHEA obtained at different growth velocities are investigated. The microstructure of the as-cast AlCoCrFeNi 2.1 EHEA is composed of bulky dendrites (NiAl phase) and lamellar eutectic structures which consists of the CoCrFeNi (FCC) phase and the NiAl (BCC) phase. Although the actual composition of the alloy is shown to slightly deviate from the eutectic point, it is interesting to observe that the full lamellar structure of this alloy is obtained through directional solidification. In order to explain this contradiction, the maximum interface temperature criterion and the interface response function (IRF) theory are applied to calculate the velocity range of the transition from the primary phase to the eutectic, which is 1.2 µm/s-2 × 104 μm/s. Furthermore, the tensile test indicates that the directionally solidified AlCoCrFeNi 2.1 EHEA possesses a good combination of strength (1340 Mpa) and ductility (30.5%) at 100 µm/s, which can be attributed to the full lamellar eutectic structure after directional solidification. In addition, the compression tests demonstrated that the compressive strength of the axial specimen is greater than the radial specimen at the same growth velocity. Thus the directional solidification can effectively adjust the alignment of the eutectic structure and achieve better mechanical properties along the growth direction. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
42. Re-Examination of the Microstructural Evolution in Undercooled Co-18.5at.%B Eutectic Alloy.
- Author
-
He, Yixuan, Wu, Yuhao, Bu, Fan, Zhang, Yiyuan, Zhang, Yifan, Hei, Bo, Zhang, Jianbao, and Wang, Haifeng
- Subjects
- *
FACE centered cubic structure , *EUTECTIC structure , *SOLIDIFICATION - Abstract
The undercooling (∆T) dependencies of the solidification pathways, microstructural evolution, and recalescence behaviors of undercooled Co-18.5at.%B eutectic alloys were systematically explored. Up to four possible solidification pathways were identified: (1) A lamellar eutectic structure consisting of the FCC–Co and Co3B phase forms, with extremely low ΔT; (2) The FCC–Co phase primarily forms, followed by the eutectic growth of the FCC–Co and Co2B phases when ΔT < 100 K; (3) As the ΔT increases further, the FCC–Co phase primarily forms, followed by the metastable Co23B6 phase with the trace of an FCC–Co and Co23B6 eutectic; (4) When the ΔT increases to 277 K, the FCC–Co phase primarily forms, followed by an FCC–Co and Co3B eutectic, which is similar in composition to the microstructure formed with low ΔT. The mechanisms of the microstructural evolution and the phase selection are interpreted on the basis of the composition segregation, the skewed coupled zone, the strain-induced transformation, and the solute trapping. Moreover, the prenucleation of the primary FCC–Co phase was also detected from an analysis of the different recalescence behaviors. The present work not only enriches our knowledge about the phase selection behavior in the undercooled Co–B system, but also provides us with guidance for controlling the microstructures and properties practically. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
43. Elastic energy of multi-component solid solutions and strain origins of phase stability in high-entropy alloys.
- Author
-
Darvishi Kamachali, Reza and Wang, Lei
- Subjects
- *
SOLID solutions , *ALLOYS , *CHEMICAL energy , *ELASTIC constants , *VALUATION of real property - Abstract
The elastic energy of mixing for multi-component solid solutions is derived by generalizing Eshelby's sphere-in-hole model. By surveying the dependence of the elastic energy on the chemical composition and lattice misfit, we derive a lattice strain coefficient λ *. Studying several high-entropy alloys and superalloys, we propose that most solid solution multi-component alloys are stable when λ * < 0.16 , generalizing the Hume-Rothery atomic-size rule for binary alloys. We also reveal that the polydispersity index δ , frequently used for describing strain in multi-component alloys, directly represents the elastic energy (e) with e = q δ 2 , q being an elastic constant. Furthermore, the effects of (i) the number and (ii) the atomic-size distribution of constituting elements on the phase stability of high-entropy alloys were quantified. The present derivations and discussions open for richer considerations of elastic effects in high-entropy alloys, offering immediate support for quantitative assessments of their thermodynamic properties and studying related strengthening mechanisms. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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