scholarly journals Effect of Thermal Vacancy on Thermodynamic Behaviors in BCC W Close to Melting Point: A Thermodynamic Study

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1648 ◽  
Author(s):  
Ying Tang ◽  
Lijun Zhang
Keyword(s):  
Melting Point ◽  
Gibbs Energy ◽  
Thermodynamic Model ◽  
Vacancy Concentration ◽  
Gibbs Energy Function ◽  
Optimization Strategy ◽  
Thermal Vacancy ◽  
Non Linear ◽  
Pure Metals ◽  
Linear Thermodynamic

As temperature increases, the thermal vacancy concentration in pure metals dramatically increases and causes some strongly non-linear thermodynamic behaviors in pure metals when close to their melting points. In this paper, we chose body-centered cubic (bcc) W as the target and presented a thermodynamic model to account for its Gibbs energy of pure bcc W from 0 K to melting point by including the contribution of thermal vacancy. A new formula for interaction part was proposed for describing the quadratic temperature behavior of vacancy formation energy. Based on the experimental/first-principles computed thermodynamic properties, all the parameters in the Gibbs energy function were assessed by following the proposed two-step optimization strategy. The thermodynamic behaviors, i.e., the strong nonlinear increase for temperature dependence of heat capacities at high temperatures and a nonlinear Arrhenius plot of vacancy concentration, in bcc W can be well reproduced by the obtained Gibbs energy. The successful description of thermal vacancy on such strongly non-linear thermodynamic behaviors in bcc W indicates that the presently proposed thermodynamic model and optimization strategy should be universal ones and are applicable to all other metals.

Real-time unstructured road detection based on CNN and Gibbs energy function

2021 ◽  
pp. 1-19
Author(s):  
Mingzhou Liu ◽  
Xin Xu ◽  
Jing Hu ◽  
Qiannan Jiang
Keyword(s):  
Gibbs Energy ◽  
Energy Function ◽  
Gaussian Mixture Models ◽  
Texture Features ◽  
Gaussian Mixture ◽  
Gibbs Energy Function ◽  
Road Detection ◽  
The Road ◽  
Detection Algorithms ◽  
Random Sample Consensus

Road detection algorithms with high robustness as well as timeliness are the basis for developing intelligent assisted driving systems. To improve the robustness as well as the timeliness of unstructured road detection, a new algorithm is proposed in this paper. First, for the first frame in the video, the homography matrix H is estimated based on the improved random sample consensus (RANSAC) algorithm for different regions in the image, and the features of H are automatically extracted using convolutional neural network (CNN), which in turn enables road detection. Secondly, in order to improve the rate of subsequent similar frame detection, the color as well as texture features of the road are extracted from the detection results of the first frame, and the corresponding Gaussian mixture models (GMMs) are constructed based on Orchard-Bouman, and then the Gibbs energy function is used to achieve road detection in subsequent frames. Finally, the above algorithm is verified in a real unstructured road scene, and the experimental results show that the algorithm is 98.4% accurate and can process 58 frames per second with 1024×960 pixels.

scholarly journals Vacancies in Pure Ice Studied by Positron Annihilation Techniques

1978 ◽  
Vol 21 (85) ◽  
pp. 85-99 ◽  
Author(s):  
O. E. Mogensen ◽  
M. Eldrup
Keyword(s):  
Hydrogen Bond ◽  
Melting Point ◽  
Positron Annihilation ◽  
Formation Energy ◽  
Vacancy Concentration ◽  
Electric Properties ◽  
Vacancy Formation Energy ◽  
Water Molecules ◽  
Pronounced Change ◽  
Electron States

Abstract Positron annihilation techniques (PAT) are briefly discussed, and the information that may be obtained about the positronium (Ps) states is compared to that obtainable about the similar electron states. The behaviour of Ps in monocrystals of pure light and heavy ice was studied at temperatures between — 185°C and the melting point. Ps is very probably trapped in vacancies (i.e. missing water molecules) in ice. A vacancy formation energy of roughly 0.2–0.35 eV was derived in agreement with the value 0.28±0.07 eV obtained previously from studies of the annealing of irradiated ice. The vacancy concentration is at least a few parts per million at the melting point, i.e. roughly 104 times higher than normally assumed in the literature. The fact that the vacancy concentration is comparable to that of the hydrogen-bond defects will probably enforce a pronounced change in the “hydrogen-bond-defects” theory of the electric properties of ice.

Thermodynamic characterization of high-temperature superconductors in the yttrium-barium-copper-oxygen system. The Y123 solid solution (Technical Report)

2000 ◽  
Vol 72 (3) ◽  
pp. 463-477 ◽  
Author(s):  
G. F. Voronin
Keyword(s):  
Solid Solution ◽  
Gibbs Energy ◽  
Thermodynamic Data ◽  
High Temperature Superconductors ◽  
Gibbs Energy Function ◽  
Data Set ◽  
Y123 Phase ◽  
Barium Copper ◽  
Self Consistent ◽  
Consistent Thermodynamic Data

The aim of this report is to inform the chemical community about a self-consistent thermodynamic data set for the YBa2 Cu3 O6+z (1 ≥ z ≥ 0) solid solution, that is well known as the Y123 phase and possesses superconducting properties at z~1 and low temperatures. About 3300 experimental points obtained in 240 miscellaneous experiments published in 78 papers have been processed simultaneously in order to obtain the most reliable Gibbs energy function of the Y123 phase in the temperature range from 250 to 1300 K and pressures up to 100 kbar. A function is recommended for approximation of the Gibbs energy, which has 16 adjustable parameters. All other thermodynamic properties of the Y123 solution, including the conditions for its internal stability, can be derived from the assessed Gibbs energy. Brief descriptions of the thermodynamic model, experimental and data assessment methods as well as examples of self-consistent thermodynamic data applications are given.

Evaluation of the Thermodynamic Properties and Phase Equilibria of the Ordered γ’ and Disordered γ Phases in the Ni-Al-Ta System

2002 ◽  
Vol 755 ◽  
Author(s):  
Shihuai Zhou ◽  
Long-Qing Chen ◽  
Rebecca A. MacKay ◽  
Zi-Kui Li u
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Phase Equilibria ◽  
Phase Diagrams ◽  
Gibbs Energy Function ◽  
Ternary Interaction ◽  
Two Phases ◽  
Rich Side ◽  
Good Agreement

ABSTRACTThe phase equilibria and thermodynamic properties of the ternary Ni-Al-Ta system on Ni-rich side were analyzed. Thermodynamic descriptions of the liquid, γ-fcc, γ'-L12, and π-Ni6AlTa phases were obtained using the CALPHAD (CALculation of PHase Diagrams) technique. The thermodynamics of γ-fcc and γ'-L12 phases were modeled with a single Gibbs energy function taking into account the crystallographic relation between the two phases. The ternary interaction parameters of the liquid and fcc phases were also determined. The calculated phase diagrams of the ternary Ni-Al-Ta system show a good agreement with experimental data.

Evaluation of Wagner Interaction Parameter in Fe-Mn-Si-Nb-Ti-V-C System

2005 ◽  
Vol 475-479 ◽  
pp. 3327-3330 ◽  
Author(s):  
Sang Hwan Lee ◽  
Kyung Sub Lee ◽  
Kyung Jong Lee
Keyword(s):  
Gibbs Energy ◽  
Thermodynamic Model ◽  
Lattice Model ◽  
Excess Gibbs Energy ◽  
Chemical Potential ◽  
Solution Model ◽  
Interaction Parameters ◽  
Dilute Solution ◽  
Relationship Of ◽  
The Relationship

The dilute solution model is quite widely used because the chemical potential is more easily defined than that in the sub-lattice model. In the present study, the thermodynamic model for the Fe-Mn-Si-Nb-Ti-V-C system was conducted by evaluating Wagner interaction parameters. The data used in this work was collected and modified by means of TCFE 2000-database in Thermo-Calc and up-to date references. The relationship of interaction parameters(L) in the sub-lattice model and Wagner interaction parameters in the dilute solution model was derived. The composition dependency of reference state and the higher order interaction parameters of the excess Gibbs energy were considered to evaluate Wagner interaction parameters. The equilibrium compositions of austenite and fractions of phases and the dissolution temperature of precipitates(NbC, VC, and TiC) were evaluated by the dilute solution model and compared with the results by the sub-lattice model.

scholarly journals Thermodynamic modeling of composition and propereties of self-fluxing materials based on the nickel

2020 ◽  
Vol 329 ◽  
pp. 02026
Author(s):  
Nina Ilinykh ◽  
Anastasia Krivorigova ◽  
Boris Gelchinski ◽  
Sergey Ilinykh ◽  
Leonid Kovalev
Keyword(s):  
Melting Point ◽  
Gibbs Energy ◽  
Condensed Phase ◽  
Software Package ◽  
Total Pressure ◽  
Thermodynamic Simulation ◽  
Thermodynamic Characteristics ◽  
Equilibrium Composition ◽  
Argon Atmosphere ◽  
Temperature Dependences

Self-fluxing nickel or cobalt-based alloys that use boron, phosphorus or silicon, as melting point depressants and fluxing agents are thermodynamic simulation of self-fluxing materials Ni-0.5C-15Cr-3.2Si-2B (PGSR-2) and Ni-1C-17Cr-4.1Si-3.6B (PGSR-4) was performed. As the software for simulation of phase and chemical equilibrium the TERRA software package was used. The simulation was carried out in the temperature range 300–3000 K at a total pressure P = 105 Pa in an argon atmosphere. The temperature dependences of the equilibrium composition and thermodynamic characteristics (enthalpy, entropy, and Gibbs energy) of the alloys of the investigated systems were calculated. It is shown that Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, CrSi can be formed in the condensed phase under equilibrium heating of PGSR-2. When PGSR-4 is heated in the condensed phase, along with the above components, Cr5B3, CrB2 and Cr3C2 compounds can be formed. The temperature dependences of the thermodynamic characteristics of the systems studied have kinks that can be explained by phase transformations.

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