scholarly journals Fractional-differential approach to describe the process of feeding metals and alloys solidifying under controlled gas pressure

2021 ◽  
Vol 4 (135) ◽  
pp. 149-155
Author(s):  
Tatjana Selivyorstova ◽  
Vadim Selivyorstov ◽  
Yuliia Mala
Keyword(s):  
Single Phase ◽  
Metals And Alloys ◽  
Phase Zone ◽  
Two Phase ◽  
Diffusion Type ◽  
Different Types ◽  
Fractional Differential ◽  
The Given ◽  
Kinetics Of ◽  
Independent Thought

To describe the processes of filtration in the folding dendritic-porous middle of the proponation, a number of fractional-differential mathematical models of the diffusion type. Described non-linear, how to take the shot of the abducted Riman-Leeuwill for an hour, as it can be stuck for a correct description of the single-phase filtration of not Newtonian age in the porous middle.The two-phase zone, which is established during the transition from melting from hard to hard mill, can often be characterized by abnormal kinetics of resistance. The peculiarities of kinetics in the whole range of winners are related to the issues of widespread nonlocality, in a number of types, memory defects, which adhere to the progressive laws. The mathe-?atical apparatus, which allows to adequately describe such processes, is the theory of integration-differentiation of the fractional order.Victorians in robotic thinking have a phenomenological character, so the possibility of their dependence in a specific, practical dermal condition is blamed on the basis of experimental results, so that the validity of other differences is confirmed. Stagnation of the given approach for describing the dynamics of the process of vitality of the two-phase zones and metals and alloys, which solidifies in the minds of a regulated gas vice. Presented in the fractional-differential robotic model of filtration are classified as abnormal diffusion. A characteristic feature of the ryvnyan, which is derived from different types of differential models of filtration, is not the same. With a whole model, they preserve the structure of the classical lines of filtration in the whole order and pass into them in boundary drops, if the order of the other differentiation is old.Vivchennya yakіsnyh authorities otrimanih іvnyans, and also prompts їh numerical decisions є to finish nontrivial zavdannyi, as vimagayut in the skin okremomu vampad of independent thought.

scholarly journals FEATURES OF THE FRACTIONAL-DIFFERENTIAL APPROACH IMPLEMENTATION TO DESCRIBE THE PROCESS OF FEEDING A TWO-PHASE ZONE DURING SOLIDIFICATION OF METALS AND ALLOYS

2021 ◽  
pp. 88-91
Author(s):  
Tatjana Selivyorstova ◽  
Vadim Selivyorstov ◽  
Yuliia Mala
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Nonlinear Equation ◽  
Mathematical Models ◽  
Single Phase ◽  
Phase Zone ◽  
Two Phase ◽  
Diffusion Type ◽  
Differential Approach ◽  
Fractional Differential

To describe filtration processes in complex dendritic-porous media, a number of fractional-differential mathematical models of diffusion type have been proposed.A nonlinear equation containing fractional Riemann-Liouville derivatives with respect to time is described, which can be used to correctly describe the single-phase filtration of a non-Newtonian fluid in a porous medium.

Tensile Property Improvements of Spinodal Cu-15Ni-8Sn by Two-Phase Heat Treatment

1982 ◽  
Vol 104 (3) ◽  
pp. 234-240 ◽  
Author(s):  
T. J. Louzon
Keyword(s):  
Heat Treatment ◽  
Single Phase ◽  
Phase Region ◽  
Two Phase ◽  
Heat Treated ◽  
Slow Kinetics ◽  
Increased Strength ◽  
Kinetics Of ◽  
Phase Solution ◽  
Strength And Ductility

A heat treatment has been developed which produces significant improvements in the tensile properties of Cu-15Ni-8Sn spinodal alloy. The treatment involves solution heat treatment in the two-phase region rather than the single-phase region normally used. After quenching and aging, increased strength and ductility of the alloy over single phase solution heat-treated and aged values were found. The mechanical properties obtained were superior to any previously observed for material of the compositions studied in the solution treated, quenched, and aged condition. Also, the alloys’ transformation kinetics were greatly slowed by the two phase heat-treatment. It is suggested that the increase in strength and slow kinetics of transformation observed are caused by grain size effects and by grain boundary modifications. Resistivity data and etching response corroborate these arguments.

An Investigation of Heat Transfer on Microchannel Heat Exchanger Flow Arrangement with Gas Heating

2011 ◽  
Vol 145 ◽  
pp. 262-266 ◽  
Author(s):  
Tsung Lin Liu ◽  
Ben Ran Fu ◽  
Chin Pan
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Single Phase ◽  
Thermal Power ◽  
Phase Zone ◽  
Two Phase ◽  
Exhaust Heat ◽  
Gas Heating ◽  
Actual Effectiveness ◽  
Counter Current

The present study investigates the effect of flow arrangement on heat transfer characteristics in two-phase microchannel heat exchangers (MCHEs) with gas heating. The microchannel heat exchangers are developed to utilize the exhaust heat from a high-temperature gas product of a methanol reformer (a part of a reformed methanol fuel cell). Co-and counter-current flow types of MCHE are tested. Working fluids in the hot and cold sides are helium and liquid methanol, respectively. For both single-phase flow regions, the experimental results indicate that the actual effectiveness of the counter-current MCHE is higher than that of the co-current MCHE. Both of the actual effectiveness of co-and counter-current MCHEs significantly increases with an increase of cold side mass flux. Moreover, the actual effectiveness for both types of MCHE is less relationship to the hot-side thermal power in single-phase zone. The highest actual effectiveness is about 0.6 and 0.72 for co-and counter-current MCHEs, respectively.

Optimisation of Precipitation for the Development of Improved Wrought Fe3Al-based Alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
Satoru Kobayashi ◽  
Stefan Zaefferer ◽  
André Schneider
Keyword(s):  
Grain Refinement ◽  
Hot Deformation ◽  
Single Phase ◽  
Fine Particles ◽  
Phase Region ◽  
Air Cooling ◽  
Two Phase ◽  
Kinetics Of ◽  
Very High ◽  
Grain Refinement Strengthening

ABSTRACTEffect of TiC precipitates on the kinetics of static recrystallisation has been studied by using a Fe-26Al-5Cr (at%) single-phase (α:A2/B2/D03) alloy and two-phase (α+TiC) alloys with different amounts of TiC precipitates. Based on the results, a desirable thermo-mechanical processing is proposed for the development of wrought Fe3Al-based alloys with strengthening MC carbides.In the alloys with a high amount of TiC, needle-like TiC precipitates with 1–10 μm in length formed during air-cooling after homogenisation. Hot deformations with such large precipitates cause inhomogeneous deformation around the particles, leading to particle stimulated nucleation (PSN) and hence accelerate recrystallisation.The occurrence of PSN is harmful for the embrittlement problem, i.e. ductility drastically decreases when recrystallisation occurs, but useful for grain refinement. The following process is proposed to accomplish grain refinement, strengthening by precipitates and avoidance of the embrittlement: hot deformation with a large amount of precipitates to make grain refinement possible by using PSN, followed by hot deformation with a small amount of precipitates near α single-phase region and a subsequent heat treatment to obtain fine precipitates. The fine particles would also act to pin the boundaries of growing grains, thus leading to extended recovery rather than recrystallisation. This process is difficult to carry out in the (Fe-26Al-5Cr)-TiC system because the temperature necessary to enable precipitation is very high and the kinetics is quick. The precipitation temperature is significantly decreased by replacing TiC by VC or MoC.

Bi-Velocity Phase Field Method

2013 ◽  
Vol 333 ◽  
pp. 83-89
Author(s):  
Bartek Wierzba ◽  
Marek Danielewski ◽  
Andrzej Nowotnik ◽  
Jan Sieniawski
Keyword(s):  
Stress Field ◽  
Phase Field ◽  
Life Time ◽  
Field Method ◽  
Phase Field Method ◽  
Phase Zone ◽  
Two Phase ◽  
Gradient Coatings ◽  
Interdiffusion Coefficients ◽  
Kinetics Of

In this paper we couple the bi-velocity with the phase field method. It deals with: (1) the different mobility of the components in the two-phase zone; (2) nonzero steps of molar volumes for each component from phase to phase and (3) the composition dependent interdiffusion coefficients. The method allows to determine the average stress field during the diffusion process, the kinetics of the reactions and estimate the entropy production. The paper presents the numerical computations of diffusion in th eNiAlCr system. The results can serve as a basis in designing gradient coatings of extended life time.

scholarly journals Кислородные вакансии и валентные состояния железа в соединениях SrFeO-=SUB=-3-delta-=/SUB=-

2020 ◽  
Vol 62 (10) ◽  
pp. 1698
Author(s):  
В.Д. Седых ◽  
О.Г. Рыбченко ◽  
Э.В. Суворов ◽  
А.И. Иванов ◽  
В.И. Кулаков
Keyword(s):  
Phase Composition ◽  
Valence State ◽  
Oxygen Vacancies ◽  
Single Phase ◽  
Two Phase ◽  
X Ray ◽  
Phase Structures ◽  
Valence States ◽  
The Given ◽  
Local Oxygen

The X-ray and Mossbauer studies of the Brownmillerite phase have been carried out in the given work and the well-known literature data on the single phase compounds with a perovskite structure in ferrite strontium SrFeO3-δ have been analyzed. It has been found out that all Fe valence states for any phase composition of ferrite strontium are determined by its local oxygen environment. It allows us to understand the behavior of Fe transition from one valence state to another when adding oxygen vacancies and to explain the Fe structural states in the SrFeO3-δ oxide including single and two-phase compositions. This approach is a more general case for description of the all known compounds and synthesized phase combinations in SrFeO3-δ and the formula considered in literature for the single-phase structures well agrees with it.

Influence of N-vynilcarbazole on the photopolymerization process and properties of epoxy-acrylate interpenetrating polymer networks

e-Polymers ◽  
2016 ◽  
Vol 16 (6) ◽  
pp. 429-435
Author(s):  
Tetiana F. Samoilenko ◽  
Natalia V. Iarova ◽  
Svitlana M. Ostapiuk ◽  
Maksym H. Tkalich ◽  
Liubov O. Vorontsova ◽  
...  
Keyword(s):  
Single Phase ◽  
Polymer Networks ◽  
Mechanical Analysis ◽  
Interpenetrating Polymer Networks ◽  
Epoxy Acrylate ◽  
Uv Lamp ◽  
Using Data ◽  
The Given ◽  
Kinetics Of ◽  
Epoxy Groups

AbstractPhotocured simultaneous epoxy-acrylate interpenetrating polymer networks (IPNs) were formed both under irradiation by UV-lamp and natural sunlight. The conversion degrees of functional groups were calculated by using data obtained from Fourier transform infrared (FTIR) spectroscopy. The influence of N-vynilcarbazole (NVC) as a photosensitizer on the kinetics of IPN photopolymerization was investigated. The conversion degrees of epoxy groups were revealed to increase significantly with the addition of NVC to the given systems. The phase morphology of IPNs was analyzed by optical and scanning electronic microscopy as well as by dynamic mechanical analysis (DMA). The data obtained using DMA method, which was used for analyzing the IPN samples with different component ratios, indicate the formation of both phase-separated and single-phase IPNs. The phase separation is occurred only in NVC-containing 50:50 IPN.

Effect of Deformation Degree on Mechanical Properties of AZ80 Magnesium Alloy

2011 ◽  
Vol 239-242 ◽  
pp. 3262-3265
Author(s):  
Xu Qing Chang ◽  
Tie Hua Ma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Single Phase ◽  
Processing Parameters ◽  
Critical Value ◽  
Phase Zone ◽  
Two Phase ◽  
Deformation Degree ◽  
Extrusion Processing ◽  
Az80 Magnesium Alloy

The mechanical properties and microstructures were investigated for AZ80 Mg alloy during plane strain compression and extrusion processing. The results show the tensile strength increases with the increasing deformation degree in the two-phase zone due to sufficient dynamic recrystallization and work-hardening effect. In single-phase zone, the tensile strength increases firstly and then does not varies basically when the deformation degree is greater than a certain critical value. This is very beneficial to optimize processing parameters to obtain microstructure with improved mechanical behavior.

Investigations of α + β → β Phase Transformation in Monotonically Heated Ti6Al7Nb Alloy / Badania Przemiany Fazowej α + β → β W Stopie Ti6Al7Nb Przy Nagrzewaniu Ciągłym

2012 ◽  
Vol 57 (4) ◽  
pp. 995-1000 ◽  
Author(s):  
R. Dąbrowski
Keyword(s):  
Phase Transformation ◽  
Single Phase ◽  
Continuous Heating ◽  
Critical Temperatures ◽  
Two Phase ◽  
Fine Needle ◽  
Β Phase ◽  
Phase Range ◽  
Alloy Microstructure ◽  
Kinetics Of

This paper presents an evaluation of critical temperatures of α + β → β phase transformation in an Ti6Al7Nb alloy occurring during heating performed by dilatometric and metallographic methods. Also, changes in the alloy microstructure during cooling down from the two-phase (α + β) and single phase (β) ranges have been analysed. In the microstructure of the alloy quenched from temperature above 1010°C (one-phase range) in water, the very fine, needle-like precipitates (presumably α’) were observed as well as abnormal grain growth of the primary β phase. The obtained results may serve for the interpretation of phase transformation occurring in the Ti6Al7Nb alloy during tempering. In future, the kinetics of the phase transformation during tempering will be investigated by original CHT (Continuous-Heating-Transformation) charts, which are commonly applied for iron-base alloys.

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