Влияние микролегирования иттрием и гафнием на прочностные характеристики и морфологию карбидной фазы сплава ЖС3ДК-ВИ при замедленной кристаллизации

There are analyzed the melts of the ZhS3DK-VI alloy with different levels of strength characteristics and the factors influencing their reduction, differences in the macro and microstructure of the alloy, the effect of the crystallization rate when pouring the melt into hot and cold ceramic molds are determined. Since when casting parts, the level of properties is determined on separately cast samples, in the technology of manufacturing samples, the casting parameters of the corresponding part must be observed, and when increasing the strength characteristics due to changing technological parameters, it is imperative to consider the possibility of changing the technology of casting parts. However, for parts of complex configuration, cast from heat-resistant nickel alloys, it is often impossible to change the technology, therefore the only way to influence the properties of the material is to use microalloying with rare earth elements, for example, yttrium and hafnium. The introduction of these alloying elements in small amounts has a positive effect on factors that reduce the properties of the ZhS3DK-VI alloy, such as the unfavorable shape and topography of the carbide phase, or even slightly change the chemical composition of carbides. The article analyzes the effect of microalloying with hafnium and yttrium on the morphology and topography of the carbide phase; positive changes in the microstructure and strength characteristics at room temperature of the heat-resistant nickel alloy ZhS3DK-VI are noted. The technology of microalloying the melt has been developed to obtain satisfactory valuesof strength characteristics in tensile tests and impact toughness at room temperature. Microalloying the ZhS3DK-VI alloy with hafnium in a concentration of 0.15...0.25 % made it possible to increase the strength characteristics on samples for mechanical tests by 10…15 %, provided that the melt was drained into hot ceramic molds and slowed down. Higher concentrations of hafnium during slow crystallization lead to the formation of eutectic phases uncharacteristic for the ZhS3DK-VI alloy, requiring a decrease in the heat treatment temperature, which, accordingly, leads to a decrease in the level of long-term strength at 850 °C.

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Cyclic Mechanical Durability of Sn3.0Ag0.5Cu Pb-Free Solder Alloy

Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology ◽

10.1115/imece2005-81171 ◽

2005 ◽

Cited By ~ 6

Author(s):

Gayatri Cuddalorepatta ◽

Abhijit Dasgupta

Keyword(s):

Room Temperature ◽

Strain Range ◽

Cyclic Strain ◽

Inelastic Strain ◽

Mechanical Tests ◽

Test System ◽

Snagcu Solder ◽

Mechanical Durability ◽

Free Solder

The isothermal mechanical durability properties of a hypoeutectic, Sn3.0Ag0.5Cu solder are presented and compared to that of near-eutectic Sn3.9Ag0.6Cu and of baseline eutectic Sn37Pb solder. Cyclic mechanical tests are performed at room temperature at various load levels, using a custom-built thermo-mechanical-microscale (TMM) test system. Both the SnAgCu solders are found to outperform the baseline Sn37Pb, with near-eutectic Sn3.9Ag0.6Cu having the best durability. These trends are found to be in agreement with similar results available in the literature for thermal cycling durability. Fatigue results are presented in terms of both cyclic strain range and cyclic work dissipation. The effect of microstructural coarsening resulting from long-term aging at room temperature is investigated by conducting similar tests at room temperature, on the aged samples. The durability of the hypoeutectic SnAgCu solder reduced on aging, with the drop being more significant for damage curves based on cyclic work dissipation, than on cyclic inelastic strain range.

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Effects of Ferrite Content on the Tensile Strength and Impact Toughness of 2.25Cr-1Mo-0.25V Steels

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.520 ◽

2010 ◽

Vol 654-656 ◽

pp. 520-523

Author(s):

Tae Kyu Kim ◽

Chang Hee Han ◽

Sung Ho Kim ◽

Hee Kyung Kwon ◽

Dong Jin Kim

Keyword(s):

Heat Treatment ◽

Tensile Strength ◽

Impact Toughness ◽

Room Temperature ◽

Tensile Tests ◽

Treatment Temperature ◽

Ferrite Content ◽

The Impact ◽

Postweld Heat ◽

Low Solubility

In order to evaluate the effects of a pro-eutectoid ferrite content on the tensile strength and impact toughness of 2.25Cr-1Mo-0.25V steels, several samples with a different area fraction of ferrite in the range from 0 to 80% were prepared by a control of cooling rate from an austenitization heat treatment temperature of 930oC. The steels were then tempered at 690oC, followed by a heat treatment at 705oC as a simulation of postweld heat treatments. The results of microstructural observation indicated that the ferrite was uniformly distributed in the bainitic matrix. The results of tensile tests revealed that the tensile strength at room temperature and 450oC was slightly reduced with the ferrite content of up to 20%, but it was considerably reduced with the ferrite content of 80%. On the other hand, the results of impact tests at -60, -80 and -100oC indicated that the impact toughness was rapidly degraded with increasing ferrite content. These results attributed to the segregation of carbides in the bainitic matrix as a result of the formation of ferrite phase with low solubility of carbon. It is concluded that the ferrite content in the 2.25Cr-1Mo-0.25V steels could exert a sensitive inference on the impact toughness rather than on tensile properties.

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High temperature oxidation and mechanical behavior of β21s and Ti6242S Ti-based alloys

MATEC Web of Conferences ◽

10.1051/matecconf/202032104011 ◽

2020 ◽

Vol 321 ◽

pp. 04011

Author(s):

Aurelie Vande Put ◽

Carole Thouron ◽

Philippe Emile ◽

Raphaëlle Peraldi ◽

Benjamin Dod ◽

...

Keyword(s):

Mechanical Behavior ◽

Room Temperature ◽

Tensile Tests ◽

Lower Amount ◽

Aircraft Industry ◽

Micro Hardness ◽

Temperature Oxidation ◽

Specific Strength ◽

High Specific Strength

Aircraft industry always looks for higher in-service temperatures and lighter structures. With a high specific strength, Ti-based alloys are good candidates for such applications. However, when exposed to oxidizing environments at high temperatures, they undergo large oxygen dissolution while forming an oxide scale, which can greatly affect their mechanical properties. Then, evaluating the oxidation resistance and mechanical behavior of such alloys is essential. In this aim, long term oxidation tests were performed under laboratory air between 500 °C and 625 °C on two Ti-based alloys: β21s, exhibiting a fully β microstructure supposed to dissolve lower amount of oxygen and nitrogen, and Ti6242S, with an α/β microstructure. The oxidized samples were characterized using XRD, Raman spectroscopy, SEM-EDS and micro-durometer. As for the mechanical behavior, tensile tests were performed at room temperature on not aged and on oxidized samples. While larger mass variations were obtained at 500 and 560 °C and up to 997 h at 625 °C for β21s, its mass variations became lower than those of Ti6242S for longer durations at 625 °C. Nevertheless, β21s exhibited thicker micro-hardness affected depths and underwent larger mechanical property modifications compared to Ti6242S.

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Fabrication and Mechanical Properties of Ni3Al-Al2O3 Composites

MRS Proceedings ◽

10.1557/proc-133-609 ◽

1988 ◽

Vol 133 ◽

Cited By ~ 2

Author(s):

C. G. McKamey ◽

G. L. Povirk ◽

J. A. Horton ◽

T. N. Tiegs ◽

E. K. Ohriner

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Matrix Material ◽

Hot Extrusion ◽

Tensile Tests ◽

Mechanical Tests ◽

Interfacial Structure ◽

High Temperature Strength ◽

Four Point Bending ◽

The Matrix

ABSTRACTThe objective of this study is to develop a metal-matrix composite based on the intermetallic alloy Ni3Al reinforced with Al2O3 fibers, with improved high-temperature strength and lower density compared to the matrix material. This paper summarizes results of initial fabrication and mechanical tests on specimens produced using IC-15 [Ni-24% Al-0.24% B (at.%)] and IC-218 [Ni-16.5% Al-8% Cr-0.4% Zr-0.1% B (at.%)], with 20 vol. % Al2O3 fibers. Fabrication methods include both hot-pressing and hot-extrusion. Mechanical tests include four-point bending and tensile tests. The integrity of the fiber-matrix interface was studied and correlated with mechanical properties. Tensile ductilities of approximately 10% at room temperature were achieved for Ni3Al/Al2O3 composites with controlled material processing and interfacial structure. Fabrication of composites by hot-extrusion produced better tensile properties at room temperature, but superplastic behavior (i.e., low strengths, high ductilities) at 1000°C.

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Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

Nuklearmedizin ◽

10.1055/s-0037-1620603 ◽

1977 ◽

Vol 16 (01) ◽

pp. 30-35 ◽

Cited By ~ 1

Author(s):

N. Agha ◽

R. B. R. Persson

Keyword(s):

Complex Formation ◽

Significant Influence ◽

Room Temperature ◽

Ph Value ◽

Maximum Activity ◽

Reduction Step ◽

Labelling Yield ◽

Different Temperatures ◽

Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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Water repellent room temperature vulcanized silicone for enhancing the long-term stability of perovskite solar cells

Solar Energy ◽

10.1016/j.solener.2021.02.035 ◽

2021 ◽

Vol 218 ◽

pp. 28-34

Author(s):

Mahmoud Samadpour ◽

Mahsa Heydari ◽

Mahdi Mohammadi ◽

Parisa Parand ◽

Nima Taghavinia

Keyword(s):

Solar Cells ◽

Room Temperature ◽

Perovskite Solar Cells ◽

Water Repellent ◽

Term Stability ◽

Long Term Stability

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Study of the Ultraviolet Effect and Thermal Analysis on Polypropylene Nonwoven Geotextile

Materials ◽

10.3390/ma14051080 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1080

Author(s):

Clever Aparecido Valentin ◽

Marcelo Kobelnik ◽

Yara Barbosa Franco ◽

Fernando Luiz Lavoie ◽

Jefferson Lins da Silva ◽

...

Keyword(s):

Uv Light ◽

Polymeric Materials ◽

Tensile Tests ◽

Thermomechanical Analysis ◽

Material Stiffness ◽

Before And After ◽

Electron Microscopy Analysis ◽

Physical Tests ◽

Nonwoven Geotextile

The use of polymeric materials such as geosynthetics in infrastructure works has been increasing over the last decades, as they bring down costs and provide long-term benefits. However, the aging of polymers raises the question of its long-term durability and for this reason researchers have been studying a sort of techniques to search for the required renewal time. This paper examined a commercial polypropylene (PP) nonwoven geotextile before and after 500 h and 1000 h exposure to ultraviolet (UV) light by performing laboratory accelerated ultraviolet-aging tests. The state of the polymeric material after UV exposure was studied through a wide set of tests, including mechanical and physical tests and thermoanalytical tests and scanning electron microscopy analysis. The calorimetric evaluations (DSC) showed distinct behaviors in sample melting points, attributed to the UV radiation effect on the aged samples. Furthermore, after exposure, the samples presented low thermal stability in the thermomechanical analysis (TMA), with a continuing decrease in their thicknesses. The tensile tests showed an increase in material stiffness after exposition. This study demonstrates that UV aging has effects on the properties of the polypropylene polymer.

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Effect of Pre-Weld Heat Treatment Temperatures on TIG Welded Microstructures on Nickel Base Superalloy, GTD-111

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.658.14 ◽

2015 ◽

Vol 658 ◽

pp. 14-18

Author(s):

Tanaporn Rojhirunsakool ◽

Duangkwan Thongpian ◽

Nutthita Chuankrerkkul ◽

Panyawat Wangyao

Keyword(s):

Heat Treatment ◽

High Temperature ◽

Heat Treatment Temperature ◽

Treatment Temperature ◽

Tig Welding ◽

Nickel Base Superalloy ◽

Nickel Base ◽

Base Superalloy ◽

Weld Heat

Nickel-base superalloys have been used as high temperature materials in land-base gas turbine application. When subjected to long term, high temperature service, large crack propagation was observed. Typical refurbishment method of these turbines is carried out by using TIG welding followed by post-weld standard heat treatment. However, new crack initiation is found in the heat-affected zone after TIG welding. Pre-weld heat treatment has been discovered to improves final γ + γ’ microstructure. This study focuses on the effect of pre-weld heat treatment temperature on final γ + γ’ microstructure. Seven different conditions of pre-weld heat treatment temperature were investigated. Scanning electron microscopy studies were carried out after pre-weld and post-weld heat treatments to compare the γ + γ’ microstructure and capture microcracks. The best pre-weld heat treatment temperature produces uniform distribution of finely dispersed γ’ precipitates in the γ matrix without post-weld crack.

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Using of Untreated Carbon Nanotubes in Cement Compositions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.865.6 ◽

2016 ◽

Vol 865 ◽

pp. 6-11 ◽

Cited By ~ 2

Author(s):

Kateryna Pushkarova ◽

Maryna Sukhanevych ◽

Artur Martsikh

Keyword(s):

Carbon Nanotubes ◽

Cement Paste ◽

Cementitious Materials ◽

Positive Influence ◽

Mechanical Tests ◽

Strength Characteristics ◽

Concrete Durability ◽

Cement Mortars ◽

Optimum Decision ◽

Cement System

One of the most important problem of concrete durability is increasing of waterproofing. Researches are devoted studying of cement mortars modified by carbon nanotubes, dispersed in plasticizers solutions. Were investigated physico-mechanical properties of cement paste, cement-sand mortar into which structure entered untreated carbon nanotubes (production of plant TM "Spetsmash" Kyiv, Ukraine) in various quantity. Were used as plasticizers in cement compositions additives substances of the various chemical nature – naphtaleneformaldehyde, melamineformaldehyde and polycarboxylate. Quantity of untreated nanotubes varied from 0,5%; 1,0% and to 1,5%. Concentration of additives was accepted taking into account recommendations of producers and made about 1% from the weight of cement. Were studied some technological processes of introduction untreated carbon nanotubes in cement system and is shown that the way of introduction of nanomodifiers has essential impact on strength characteristics of cementitious materials. Optimum decision introduction of untreated carbon nanotubes is using its in dispersion plasticizer of the working concentration prepared in an ultrasonic dispergator is established. Results of physico-mechanical tests of cement paste and cement-sand mortar showed positive influence at introduction of untreated carbon nanotubes as cement modifiers on strength characteristics of samples. Resalts is shown that the nanomodifier, used quantity about 1% in solution of lignosulfonate with polycarboxylate and melamineformaldehyde plasticizer has great impact on strength characteristics.

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