scholarly journals Oxidation and Microstructural Behaviors of Ni-Based Alloys Strengthened by (Ta, Hf)C Carbides at 1250 °C in Air

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 159
Author(s):  
Patrice Berthod ◽  
Dame Assane Kane ◽  
Lionel Aranda
Keyword(s):  
Mass Gain ◽  
Cast State ◽  
Isothermal Exposure ◽  
Low Resistance ◽  
Oxidation Test ◽  
Oxide Spallation ◽  
Limited Mass ◽  
Mass Gain Rates

Two alloys based on nickel and designed to be reinforced by MC carbides thanks to the presence of Hf and Ta were produced by casting. They were subjected to 50 h-long isothermal exposure at 1250 °C in synthetic air with thermogravimetric monitoring of the oxidation progress. In the as-cast state, they contain both significant quantities of (Hf,Ta)C carbides. Their verified melting start temperatures, close to 1300 °C, allowed performing the planned oxidation test. The two alloys demonstrated a chromia-forming behavior with limited mass gain rates. However, they also showed a rather low resistance to oxide spallation at cooling, which is in proportion with the Ta/Hf ratio. After 50 h at 1250 °C, the morphology of the carbides had significantly evolved, from their initial script-like shape to a fragmented and coalesced state. The results are promising, but the use of these alloys at 1250 °C needs further improvements on the mechanical level.

scholarly journals A Short Review on the Phase Structures, Oxidation Kinetics, and Mechanical Properties of Complex Ti-Al Alloys

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1677
Author(s):  
Hooi Peng Lim ◽  
Willey Yun Hsien Liew ◽  
Gan Jet Hong Melvin ◽  
Zhong-Tao Jiang
Keyword(s):  
Mechanical Properties ◽  
Oxidation Kinetics ◽  
Mass Gain ◽  
Short Review ◽  
Al Alloys ◽  
Alloying Elements ◽  
Isothermal Exposure ◽  
Solid Solution Strengthening ◽  
Phase Structures ◽  
Solution Strengthening

This paper reviews the phase structures and oxidation kinetics of complex Ti-Al alloys at oxidation temperatures in the range of 600–1000 °C. The mass gain and parabolic rate constants of the alloys under isothermal exposure at 100 h (or equivalent to cyclic exposure for 300 cycles) is compared. Of the alloying elements investigated, Si appeared to be the most effective in improving the oxidation resistance of Ti-Al alloys at high temperatures. The effect of alloying elements on the mechanical properties of Ti-Al alloys is also discussed. Significant improvement of the mechanical properties of Ti-Al alloys by element additions has been observed through the formation of new phases, grain refinement, and solid solution strengthening.

scholarly journals Kinetic and Metallography Study of the Oxidation at 1250 °C of {Co+Ni}-Based Superalloys Containing Ti to Form MC Carbides

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Patrice Berthod ◽  
Synthia Annick Ozouaki Wora ◽  
Lionel Aranda ◽  
Ghouti Medjahdi ◽  
Erwan Etienne
Keyword(s):  
Mass Gain ◽  
Isothermal Oxidation ◽  
Chromia Scale ◽  
Continuous Scale ◽  
Different Types ◽  
Oxide Spallation ◽  
Oxidation In Air ◽  
Chromia Volatilization ◽  
Cobalt And Nickel

Six conventionally cast chromium-rich titanium-containing alloys based on cobalt and nickel with various Co/Ni ratios were considered. They were tested in oxidation in air at 1250 °C for 70 h in a thermo-balance. The mass gain curves were exploited to specify different types of kinetic constants as well as several parameters characterizing the oxide spallation occurring during cooling. The obtained results show that, the higher the Ni content, the slower the mass gain and the better the quality of the protective external chromia scale. Secondly, no dependence of the oxide spallation characteristics on the Co content was clearly noted. Globally, the isothermal oxidation behavior becomes better when Ni is more and more present at the expense of Co. Titanium seems to be playing a particular role in the process of oxidation. It notably leads to the presence of an external thin TiO2 continuous scale beyond the chromia scale. The thermogravimetry records were numerically treated to determine the parabolic constant and the chromia volatilization constant. The values of these constants evidenced a double tendency: chromia growth acceleration and chromia volatilization slow-down. These trends are to be confirmed and further investigated.

Effect of Ta on the Oxidation Resistance of a Cast Nickel-Base Die Material with Low Cr and High W Content

2005 ◽  
Vol 475-479 ◽  
pp. 669-672
Author(s):  
Qing Li ◽  
Cheng Bo Xiao ◽  
Jin Xia Song ◽  
Ding Gang Wang ◽  
Ya Fang Han
Keyword(s):  
Oxidation Resistance ◽  
Protective Layer ◽  
Mass Gain ◽  
Nickel Base Superalloy ◽  
Temperature Oxidation ◽  
Isothermal Forging ◽  
Oxidation Test ◽  
Die Material ◽  
Nickel Base ◽  
Forging Die

A conventional cast nickel-base superalloy with the chemical composition of Ni-16W-2Mo-1.5Cr-6Al wt % has been recently developed as isothermal forging die material operating at temperatures above 1000°C. The oxidation test results showed that the oxide scale spalled heavily after exposure in air at 1050°C for 100 h, which is unacceptable for the process of isothermal forging. To improve the high temperature oxidation resistance, 3 wt% Ta was added into the alloy. Specimens after oxidation test were analyzed by the scanning electron microscope (SEM) and the X-ray diffraction analysis (XRD). The results showed that the oxides were mainly NiO, NiWO4, and NiAl2O4 for all the samples. The oxidation resistance of the alloy with 3wt%Ta was fairly good at 1050°C with the mass gain rate of around 0.016g/m2•h and spallation of oxides less than 2g/m2 within 100h.The SEM results showed that a continuous protective layer of Al2O3 has been formed under the layer of NiO for the alloy containing Ta.

scholarly journals Firmicutes and Bacteroidetes explain mass gain variation in an obligate hibernator

2021 ◽  
Author(s):  
Gina Clarise Johnson ◽  
Samuel Degregori ◽  
Paul H Barber ◽  
Daniel T Blumstein
Keyword(s):  
Mass Gain ◽  
Vital Role ◽  
Lower Mass ◽  
Active Season ◽  
Symbiotic Microorganisms ◽  
Individual Fitness ◽  
Gain Variation ◽  
In The Wild ◽  
Taxonomic Groups ◽  
Mass Gain Rates

Body condition is an important life history challenge that directly impacts individual fitness and is particularly important for hibernating animals, whose maintenance of adequate body fat and mass is essential for survival. It is well documented that symbiotic microorganisms play a vital role in animal physiology and behaviour. Recent work demonstrates that gut microbes are associated with fat accumulation and obesity; Firmicutes is consistently associated with obesity while Bacteroidetes is associated with leanness both in humans and other animals.The focus of most microbiome studies has been on human health or involved lab reared animals used as a model system. However, these microbes likely are important for individual fitness in wild populations and provide potential mechanistic insights into the adaptability and survival of wildlife. Here we test whether symbiotic microorganisms within the phyla of Firmicutes and Bacteroidetes are associated with summer mass gain in an exceptionally well-studied wild population of yellow-bellied marmots (Marmota flaviventer) by quantifying microbial abundance over five years of fecal samples (2015 - 2019) collected during their summer active season. Results show that marmots with higher mass gain rates have a greater abundance of Firmicutes. In contrast, higher abundance of Bacteroidetes was associated with lower mass gain rates, but only for marmots living in harsher environments. Similar patterns were found at the family level where Ruminococcaceae, a member of Firmicutes, was associated with higher mass gain rates, and Muribaculaceae, a member of Bacteroidetes, was associated with lower mass gain rates, and similarly in harsher environments. Although correlative, these results highlight the importance of symbiotic gut microbiota to mass gain in the wild, a trait associated with survival and fitness in many taxonomic groups.

The Effect of Ultrasonic Treatment on the Oxidation Resistance and Microstructure of Fe80Cr20 Alloy Powder at High Temperature Oxidation Process

2015 ◽  
Vol 1087 ◽  
pp. 126-130
Author(s):  
Dafit Feriyanto ◽  
Maizlinda Izwana Idris ◽  
Darwin Sebayang
Keyword(s):  
Surface Morphology ◽  
Oxidation Resistance ◽  
Ultrasonic Treatment ◽  
Alloy Powder ◽  
Parabolic Rate Constant ◽  
Mass Gain ◽  
Raw Material ◽  
Ultrasonic Technique ◽  
Temperature Oxidation ◽  
Oxidation Test

Effect of ultrasonic treatment on the oxidation kinetics and microstructure of Fe80Cr20alloy is investigated. The aim of this study is to improve the surface morphology and oxidation resistance of the Fe80Cr20alloy powder as a raw material. Ultrasonic technique is very promise technology and not yet fully explored. The Fe80Cr20material was treated by ultrasonic technique (UT) at various times of 3.5 h, 4.5 h, 5 h and followed by cold compaction with force of 13 Newton. The oxidation test was carried out using tube furnace under argon gas environment with 5 cycles, which has been considered. It was found that the UT has improved the surface morphology of the material effectively. Ultrasonic was revealed that the good interparticle bonding when experimented with ultrasonic treatment at 4.5 h. In the oxidation test, the lowest mass gain of 68 mg/cm2was found at the oxidation time of 100 h. Meanwhile, the lowest parabolic rate constant of 6.8198 x 10-14g2cm-4s-1was revealed when ultrasonic for 4.5 h sample.

Adhesion of Oxides Grown in Supercritical Water on Selected Austenitic and Ferritic/Martensitic Alloys

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
D. Artymowicz ◽  
C. Bradley ◽  
B. Xing ◽  
R. C. Newman
Keyword(s):  
Supercritical Water ◽  
Thick Layer ◽  
Mass Gain ◽  
Qualitative Comparison ◽  
Ferritic Alloys ◽  
X Ray ◽  
Surface Finishes ◽  
Austenitic Alloys ◽  
Oxide Spallation ◽  
Oxide Adhesion

A series of austenitic alloys (800H, H214, I625, 310S, and 347) with different surface finishes were exposed to supercritical water (SCW) at 550 °C and 2.5 × 107 Pa for 120 h, 260 h, and 450 h in a static autoclave with an initial level of dissolved oxygen of 8 ppm. Indentation with a hardness indenter was used for assessment of oxide adhesion. This was compared with the results of a similar test on SCW-oxidized ferritic alloys. Delamination in all the tested ferritic alloys was insufficient for quantification of the results but allowed for qualitative comparison within this group. In the set of austenitic alloys, oxide on stainless steel (SS) 347 exfoliated during cooling from 550 °C, and from the remaining four alloys, only oxide on H214 delaminated, which made the qualitative comparison across the whole group impossible. Energy dispersive X-ray spectroscopy (EDX) revealed that under delaminated external Cr2O3 on H214 alloy, there was a submicron thick layer of Al-rich oxide. To investigate a possible oxide spallation on austenitic samples during exposure, mass loss obtained through descaling was compared with mass gain due to SCW exposure. The results indicated that the applied descaling procedure did not, in most cases, fully remove the scale. Apart from one case (SS 347 with alumina surface finish), there was no clear indication of oxide spallation.

scholarly journals Discontinuities in Oxidation Kinetics: A New Model and its Application to Cr–Si-Base Alloys

2021 ◽  
Author(s):  
Anke S. Ulrich ◽  
Uwe Glatzel ◽  
Mathias C. Galetz
Keyword(s):  
Oxide Scale ◽  
Oxidation Kinetics ◽  
Parabolic Rate Constant ◽  
Mass Gain ◽  
Linear Mass ◽  
Isothermal Exposure ◽  
Growth Stresses ◽  
Scale Failure ◽  
Insight Into ◽  
Rapid Mass

AbstractSome alloys such as many Cr-based systems show mass gain discontinuities during thermogravimetric measurements which strongly affect the oxidation kinetics. The behaviour cannot be described by the current models available in the literature. Thus, a novel $$k_\mathrm{para}$$ k para –$$k_\mathrm{lin}$$ k lin -P-model was developed to describe oxidation kinetics during the isothermal exposure of materials which show such behaviour. Beside the parabolic rate constant $$k_\mathrm{para}$$ k para and the linear mass loss constant $$k_\mathrm{lin}$$ k lin , the P-value and $$f_P$$ f P are introduced to take into account spontaneous rapid mass gains due to local oxide scale failure. The parameter P serves as a measure for the mass gain due to discontinuous events and $$f_P$$ f P is the frequency of such events. The both parameters can be related to oxide scale detachment and growth stresses. The application of the model is demonstrated for the oxidation of Cr–Si-based alloys in synthetic air at $$1200^{\circ }\hbox {C}$$ 1200 ∘ C for 100 h. For these alloys, the origin of the mass gain discontinuities is discussed and the meaning of P and $$f_P$$ f P is explained in more detail. Using this newly developed model, an insight into growth and nitridation resistance of oxide scales as well as scale adhesion is gained.

High-temperature oxidation of the dissimilar weld between AISI 304L and Fe-15.6Cr-8.5Mn using Ar and Ar-4%N2 shielding gas

2019 ◽  
Vol 66 (2) ◽  
pp. 210-214
Author(s):  
Somrerk Chandra-Ambhorn ◽  
Sompong Chueaprakha ◽  
Thamrongsin Siripongsakul
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Shielding Gas ◽  
Aisi 304L ◽  
Content Type ◽  
Oxidation Test ◽  
Dissolved Nitrogen ◽  
Dissimilar Welds

Purpose The dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were investigated on oxidation at 700°C with the effects of dissolved nitrogen in the welds. This paper aims to clarify the oxidation behaviors to expand the range of application for Fe-Cr-Mn stainless steel. Design/methodology/approach Dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were fabricated using gas tungsten arc welding to investigate the oxidation behavior of the welds at 700°C. Pure Ar and Ar-4%N2 shielding gases were used to evaluate the effects of nitrogen gas. The welds were introduced to the cyclic oxidation test. In each cycle, the furnace was heated up to 700°C, and the temperature was kept at 700°C for 8 h, then the mass gain because of oxidation was examined. The scales after oxidation test were investigated by using scanning electron microscopy with EDX and X-ray diffraction analysis. Findings Addition of 4 per cent nitrogen to Ar shielding gas reduced delta-ferrite content in the weld. Ar-4%N2 shielding gas resulted in dissolved nitrogen which helped increase the diffusivities of chromium or oxygen vacancies in the oxide to facilitate the chromia formation at the inner part near the steel substrate. This protective layer can help reduce the Fe outward diffusion, thus reducing mass gain because of iron oxide formation. Originality/value The oxidation behavior of dissimilar welds between AISI 304L and Fe-15.6Cr-8.5Mn were investigated at 700°C. The evaluation is beneficial for expanding the range of application of Fe-Cr-Mn stainless steel at high temperature.

The Influence of Praseodymium Content on the Hydrogen Absorption Capability of PrFeCoBNb Magnetic Alloys

2010 ◽  
Vol 660-661 ◽  
pp. 296-301
Author(s):  
E.A. Périgo ◽  
Gabriel Souza Galdino ◽  
Jivaldo R. Matos ◽  
Hidetoshi Takiishi ◽  
Rubens Nunes de Faria Jr.
Keyword(s):  
Satisfactory Agreement ◽  
Closed System ◽  
Hydrogen Absorption ◽  
Hydrogen Pressure ◽  
Mass Gain ◽  
Magnetic Alloy ◽  
Cast State ◽  
Magnetic Alloys ◽  
Pressure Decrease

The hydrogen absorption capability of PrxFe77.9-xCo16.0B6.0Nb0.1 (12.0 ≤ x ≤ 14.0) magnetic alloys was evaluated. A practical methodology was developed so that the hydrogen pressure decrease inside a closed system was correlated to the mass gain (%W) of the sample. %W increases linearly with the Pr concentration in the magnetic alloy either in the as-cast state or annealed during 20 hours at 1070°C. Comparisons between %Wtheoretical and %Wexperimental showed a satisfactory agreement.

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