Influence of alloying systems on the properties of single crystal nickel-based superalloys

2021 ◽  
Vol 112 (10) ◽  
pp. 794-799
Author(s):  
Alexander Glotka ◽  
Vadim Ol’shanetskii
Keyword(s):  
Single Crystal ◽  
Regression Models ◽  
Strength Properties ◽  
Term Limits ◽  
Alloying Elements ◽  
Structure Stability ◽  
Plastic Properties ◽  
Crystal Lattices ◽  
Predictive Regression ◽  
First Time

Abstract The purpose of the investigation was to obtain the predictive regression models that help correct the calculation of the mechanical properties of single crystal nickel-based superalloys without conducting prior experiments. The paper considers the influence of alloying elements on their tendency to form phases in foundry nickel-based superalloys. Using the elements influence on the phase formation, the coefficient Kc’ of the ratio of alloying elements for this class of alloys was set for the first time. We have revealed the short correlation of the ratio Kc’ with the dimensional misfit of γ and γ’ crystal lattices. Also, a high probability to predict the misfit for multicomponent nickel systems is shown, which significantly affected the strength properties. The regression models of correlation dependencies on the dimensional γ/γ’- misfit were offered to predict the short-term and long-term limits of the strength of alloys. We determined the operating temperature at which the misfit value should decrease to zero. The structure stability should increase because of the structural stresses minimizing. This has a positive effect on strength and plastic properties.

scholarly journals Properties of nickel-based superalloys of equiaxial crystallization

2021 ◽  
pp. 19-23
Author(s):  
O. Glotka ◽  
V. Olshanetskii
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Regression Models ◽  
Computational Prediction ◽  
Integrated Approach ◽  
Experimental Data Processing ◽  
Predictive Regression ◽  
Heat Resistant ◽  
First Time ◽  
Thermodynamic Processes

Purpose. The aim of the work is to obtain predictive regression models, with the help of which, it is possible to adequately calculate the mechanical properties of nickel-based superalloys of equiaxial crystallization, without carrying out preliminary experiments. Research methods. To find regularities and calculate  the latest CALPHAD method was chosen, and modeling of thermodynamic processes of phase crystallization was performed. Results. As a result of experimental data processing, the ratio of alloying elements Kg¢ was proposed for the first time, which can be used to assess the mechanical properties, taking into account the complex effect of the main alloy components. The regularities of the influence of the composition on the properties of heat-resistant nickel alloys of equiaxial crystallization are established. The analysis of the received dependences in comparison with practical results is carried out. The relations well correlated with heat resistance, mismatch and strength of alloys are obtained. Scientific novelty. It is shown that for multicomponent nickel systems it is possible with a high probability to predict a mismatch, which significantly affects the strength characteristics of alloys of this class. The regularities of the influence of the chemical composition on the structure and properties of alloys are established. A promising and effective direction in solving the problem of predicting the main characteristics of heat-resistant materials based on nickel is shown Practical value. On the basis of an integrated approach for multicomponent heat-resistant nickel-based alloys, new regression models have been obtained that make it possible to adequately predict the properties of the chemical composition of the alloy, which made it possible to solve the problem of computational prediction of properties from the chemical composition of the alloy. This allows not only to design new nickel-based alloys, but also to optimize the composition of existing brands.

scholarly journals PREDICTION THERMO-PHYSICAL CHARACTERISTICS HEAT-RESISTANT NICKEL ALLOYS DIRECTIONAL CRYSTALLIZATION

2021 ◽  
Vol 27 (2) ◽  
pp. 68-71
Author(s):  
Alexander Glotka ◽  
Vadim Ol'shanetskii
Keyword(s):  
Regression Models ◽  
Nickel Alloys ◽  
Alloying Elements ◽  
Critical Temperatures ◽  
Alloying System ◽  
Heat Resistant ◽  
First Time ◽  
Good Agreement ◽  
Thermodynamic Processes ◽  
Effect Of Alloying

The thermodynamic processes of phase separation are modeled, which significantly affect the temperature characteristics of heat-resistant nickel alloys of directional solidification. Using an empirical approach, new ratios of elements Kg¢ and Kg have been obtained for the first time, which take into account the combined effect of alloying elements on the temperature of multicomponent compositions of cast heat-resistant alloys. The calculated values of the critical temperatures for the Ni-6Al-9Co-8W-4Re-4Ta-1.5Nb-1Mo-0.15C system (ZhS32-VI, ZhS32B-VI, and ZhS32E-VI alloys) are in good agreement with the experimental ones. The dependences of the Kg ratio on the alloying system are constructed, and the effect of alloying on the liquidus temperature of alloys is investigated. The ratios of the content of alloying elements and regression models that can be used to predict the width of the temperature range of crystallization and the optimal temperature of homogenization for a particular alloy are presented.

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

scholarly journals Microstructure and Properties of TiAl-Based Alloys Melted in Graphite Crucible

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 669
Author(s):  
Wojciech Szkliniarz ◽  
Agnieszka Szkliniarz
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Graphite Crucible ◽  
Strength Properties ◽  
Operating Conditions ◽  
Vacuum Induction Furnace ◽  
Intermetallic Alloys ◽  
Plastic Properties ◽  
Similar Chemical ◽  
Crucible Furnace ◽  
Successive Generations

This paper presents the chemical and phase composition, microstructure, and selected properties both at room temperature and at the temperature corresponding to the expected operating conditions of three successive generations of TiAl-based alloys (Ti-47Al-2W-0.5Si, Ti-45Al-8Nb-0.5(B,C), and Ti-45Al-5Nb-2Cr-1Mo-0.5(B,C)-0.2Si) melted in a vacuum induction furnace with high-density isostatic pressed graphite crucibles. The obtained results of mechanical and physical properties of the produced alloys were compared to the properties of reference alloys with similar chemical composition and melted in a cold copper crucible furnace. The effect of increased carbon content in the produced alloys due to the degradation of the graphite crucible during melting is higher strength properties, lower plastic properties, higher coefficient of thermal expansion, and improved creep resistance. It was shown that the proposed technology could be successfully used in the production of different generation TiAl-based intermetallic alloys.

Solid-state dynamics and single-crystal to single-crystal structural transformations in octakis(3-chloropropyl)octasilsesquioxane and octavinyloctasilsesquioxane

2017 ◽  
Vol 19 (40) ◽  
pp. 27516-27529 ◽  
Author(s):  
A. Kowalewska ◽  
M. Nowacka ◽  
M. Włodarska ◽  
B. Zgardzińska ◽  
R. Zaleski ◽  
...  
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Structural Transformations ◽  
Crystal Lattices ◽  
Thermally Induced ◽  
Crystal Structural

Thermally induced formation of symmetric crystal lattices in functional POSS proceeds via different mechanisms and results in unique reversible phenomena.

Render unto Caesar Just a Little Bit Longer: The Relationship between Constitutional Reforms and Executive Survival

2021 ◽  
pp. 1-22
Author(s):  
Tofigh Maboudi ◽  
Ghazal P. Nadi ◽  
Todd A. Eisenstadt
Keyword(s):  
Term Limits ◽  
Institutional Constraints ◽  
Third Wave ◽  
Political Leaders ◽  
Constitutional Order ◽  
The Third ◽  
Constitutional Reforms ◽  
The Impact ◽  
First Time ◽  
The Relationship

Abstract Since the third wave of democracy, term limits have become a popular fixture of most constitutions intended to constrain the executive. Yet, recent constitutional reforms around the world show that presidents seeking re-election sometimes overturn the entire constitutional order to extend their power. What is the impact of these constitutional manipulations on the longevity of the executive in office? Using survival analysis of all political leaders and national constitutions from 1875 to 2015, this article demonstrates, for the first time, that when ‘authoritarian-aspiring’ presidents remove constitutional term limits, they increase their stay in office by more than 40%. Our findings contrast with a widely held position in the comparative authoritarian literature suggesting that dictators survive longer under institutional constraints. On the contrary, we argue that by removing constitutional barriers, rulers consolidate more power at the expense of their most ambitious allies and can stay in power longer.

The effect of device geometry and crystal orientation on the stress-dependent offset voltage of 3C–SiC(100) four terminal devices

2015 ◽  
Vol 3 (34) ◽  
pp. 8804-8809 ◽  
Author(s):  
Afzaal Qamar ◽  
Hoang-Phuong Phan ◽  
Jisheng Han ◽  
Philip Tanner ◽  
Toan Dinh ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Orientation ◽  
Offset Voltage ◽  
Device Geometry ◽  
Stress Dependent ◽  
P Type ◽  
The Impact ◽  
First Time

This communication reports for the first time, the impact of device geometry on the stress-dependent offset voltage of single crystal p-type 3C–SiC four terminal devices.

scholarly journals Simulation of the External Pressure Influence on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 247-252
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Suzana Gomes Fries ◽  
Ingo Steinbach ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Microstructural Evolution ◽  
Phase Field ◽  
Structural Evolution ◽  
Field Method ◽  
External Pressure ◽  
Experimental Results ◽  
Alloying Elements ◽  
Phase Field Method

The phase field method has been applied to simulate the microstructural evolution of a commercial single crystal Ni-based superalloy during both, HIP and annealing treatments. The effects of applying high isostatic pressure on the microstructural evolution, which mainly retards the diffusion of the alloying elements causing the loss of the orientational coherency between the phases is demonstrated by the simulation and experimental results

scholarly journals Protein crystal lattices are dynamic assemblies: the role of conformational entropy in the protein condensed phase

IUCrJ ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 130-140 ◽  
Author(s):  
Margarita Dimova ◽  
Yancho D. Devedjiev
Keyword(s):  
Condensed Phase ◽  
Protein Structures ◽  
Van Der Waals Interactions ◽  
Protein Crystal ◽  
Crystal Formation ◽  
Conformational Entropy ◽  
Crystal Lattices ◽  
Crystal Contacts ◽  
First Time

Until recently, the occurrence of conformational entropy in protein crystal contacts was considered to be a very unlikely event. A study based on the most accurately refined protein structures demonstrated that side-chain conformational entropy and static disorder might be common in protein crystal lattices. The present investigation uses structures refined using ensemble refinement to show that although paradoxical, conformational entropy is likely to be the major factor in the emergence and integrity of the protein condensed phase. This study reveals that the role of shape entropy and local entropic forces expands beyond the onset of crystallization. For the first time, the complete pattern of intermolecular interactions by protein atoms in crystal lattices is presented, which shows that van der Waals interactions dominate in crystal formation.

scholarly journals Методы оценки продуктивности представителей рода эхинацея (Echinacea Moench) прегенеративного периода онтогенеза

2013 ◽  
pp. 24-30
Author(s):  
С. В. Поспелов
Keyword(s):  
Regression Models ◽  
Input Data ◽  
Growing Season ◽  
Echinacea Purpurea ◽  
System Productivity ◽  
Aerial Parts ◽  
Purple Coneflower ◽  
Echinacea Pallida ◽  
First Time

За багаторічними дослідженнями ехінацеї пурпурової (Echinacea purpurea (L.) Moench,) сорту Зірка Миколи Вавилова та ехінацеї блідої (Echinacea pallida (Nutt.) Nutt.) сорту Красуня Прерій вперше розроблені й запатентовані методи визначення продуктивності рослин прегенеративного періоду онтогенезу. Методики засновані на регресійних моделях із високими коефіцієнтами детермінації, на підставі яких можна без пошкодження рослин провести оцінку продуктивності надземної частини та кореневої системи протягом веґетаційного періоду. Вихідними даними для розрахунків слугують показники довжини і ширини листковоїпластинки, їх кількість, а також сума температур вище 5 0С і кількість діб від сівби. On the basis of long-term researches of Purple Coneflower (Echinacea purpurea (L.) Moench) variety «Zirka Mykoly Vavylova» and Pale Coneflower (Echinacea pallida (Nutt.) variety «Krasunja Preriy» for the first time ever there were developed and patented the methods for determining the efficiency of plants in pregenesic period of ontogeny. The foundation of methodology was made on the studies of regression models with high coefficients of determination which allow to make the estimation of aerial parts and root system productivity for the whole growing season without damaging the plants. The input data for the calculation are the indicators of the length and width of the leaf blade, the amount and the sum of temperatures above + 5 ºC and the number of days from sowing.

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