Influence of Zr Addition on Oxidation Behavior of TiAl-Based Alloys

2011 ◽  
Vol 696 ◽  
pp. 360-365 ◽  
Author(s):  
Michiko Yoshihara
Keyword(s):  
Oxide Scale ◽  
Oxidation Behavior ◽  
Binary Alloys ◽  
High Growth ◽  
Mass Gain ◽  
High Growth Rate ◽  
Scale Spallation ◽  
Zr Addition ◽  
Poor Oxidation Resistance

The alloys based on γ-TiAl have attractive properties as light weight heat-resisting material. The poor oxidation resistance is one of the drawbacks to limit their application. This results from the high growth rate of TiO2 in the scale and the spallation of the oxide scale during cooling. In the present study, the influence of Zr addition on the oxidation behavior of TiAl has been investigated with emphasis on scale adherence. The oxidation behavior of Ti-45Al (in mol %), Ti-45Al-6Nb alloys containing 0 - 0.2% Zr, Ti-Nb and Ti-Zr binary alloys were investigated. The oxide scale was analyzed by conventional methods including X-ray diffractometry, SEM and EPMA. The addition of Nb to TiAl results in a remarkable decrease in mass gain, while the Zr addition to TiAl results in a slight decrease. The Ti-45Al-Nb alloy with Zr shows scale spallation after long term exposure. Concerning the binary alloys, the addition of Zr to Ti more than 20 mol% accelerates the oxide growth significantly. The XRD for Ti-45Al-6Nb-0.2Zr after oxidation shows the formation of Zr oxides and Ti-Zr complex oxides in the scale. The scale spallation observed in this alloy is due to the enrichment of Zr at scale / alloy interface and formation of Zr oxide in the scale.

scholarly journals Effect of Cr and Al alloying on the oxidation resistance of a Ti5Si3-incorporated MoSiBTiC alloy

2021 ◽  
Vol 40 (1) ◽  
pp. 204-213
Author(s):  
Xi Nan ◽  
Tomotaka Hatakeyama ◽  
Shuntaro Ida ◽  
Nobuaki Sekido ◽  
Kyosuke Yoshimi
Keyword(s):  
Solid Solution ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Oxide Scales ◽  
Accelerated Oxidation ◽  
Oxidation Test ◽  
Poor Oxidation Resistance

Abstract The effects of adding Cr and Al on the oxidation behavior of a Ti5Si3-incorporated MoSiBTiC alloy (46Mo–28Ti–14Si–6C–6B, at%) were investigated at 800 and 1,100°C. The addition of Cr and Al largely improved the oxidation resistance of the MoSiBTiC alloy at 800°C due to the formation of Cr2(MoO4)3 and Al2(MoO4)3 in the oxide scales. These protective molybdates mainly formed on the molybdenum solid solution (Moss) and Mo3Si phases that show poor oxidation resistance in the Cr- and Al-free alloy and consequently increased the oxidation resistance of the alloys. However, accelerated oxidation occurred on the 10Al alloy after the long-term oxidation test, suggesting that the formed oxide scale has limited protection ability. At 1,100°C, the addition of Cr and Al also enhanced the oxidation resistance to some extent by forming Cr2O3 and Al2O3 in the oxide scales.

Oxidation Of AI-Cu-Fe Quasicrystals

1998 ◽  
Vol 553 ◽  
Author(s):  
B. I. Wehner ◽  
U. Köster
Keyword(s):  
Oxide Layer ◽  
Oxidation Behavior ◽  
Copper Ions ◽  
High Growth ◽  
High Growth Rate ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Concentration Changes ◽  
High Temperature Oxidation Behavior ◽  
In The Beginning

AbstractThe oxidation behavior of i-A163Cu25Fe12 at 800°C in air was investigated by means of TGA, XRD, SEM and TEM. In the beginning a homogeneous oxide layer is formed by the subsequent growth of metastable γ-Al2O3 and Θ-Al2O3. Nucleation of the thermodynamical stable α-Al2O3 occurs at the interface oxide/quasicrystal. The following growth of α-Al2O3 through the oxide layer leads to the formation of oxide nodules. The high growth rate of the α-Al2O3 can be explained by the incorporation of copper ions. The oxidation resistance of the quasicrystal is insufficient at high temperatures, because no protective oxide layer is formed. The high temperature oxidation behavior of Al-Cu-Fe quasicrystal and the aluminides β-FeAl and β-NiAl is compared regarding the oxidation rate, the oxide phases and the concentration changes in the material due to selective oxidation of aluminum.

scholarly journals High Temperature Oxidation Behavior of Selective Laser Melting Manufactured IN 625

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 668 ◽  
Author(s):  
Mihaela Raluca Condruz ◽  
Gheorghe Matache ◽  
Alexandru Paraschiv ◽  
Teodor Badea ◽  
Viorel Badilita
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Selective Laser Melting ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Complex Oxide ◽  
Mass Gain ◽  
Laser Melting ◽  
Temperature Oxidation ◽  
High Temperature Oxidation Behavior

The high-temperature oxidation behavior of selective laser melting (SLM) manufactured IN 625 was studied over 96 h of exposure at 900 °C and 1050 °C in air. An extensive analysis was performed to characterize the oxide scale formed and its evolution during the 96 h, including mass gain analysis, EDS, XRD, and morphological analysis of the oxide scale. The mass gain rate of the bare material increases rapidly during the first 8 h of temperature holding and diminishes at higher holding periods for both oxidation temperatures. High-temperature exposure for short periods (24 h) follows a parabolic law and promotes the precipitation of δ phase, Ni-rich intermetallics, and carbides. Within the first 24 h of exposure at 900 °C, a Cr2O3 and a (Ni, Fe)Cr2O4 spinel scale were formed, while at a higher temperature, a more complex oxide was registered, consisting of (Ni, Fe)Cr2O4, Cr2O3, and rutile-type oxides. Prolonged exposure of IN 625 at 900 °C induces the preservation of the Cr2O3 scale and the dissolution of carbides. Other phases and intermetallics, such as γ, δ phases, and MoNi4 are still present. The exposure for 96 h at 1050 °C led to the dissolution of all intermetallics, while the same complex oxide scale was formed.

scholarly journals Role of hypothalamic tanycytes in nutrient sensing and energy balance

2018 ◽  
Vol 78 (3) ◽  
pp. 272-278
Author(s):  
Marco Travaglio ◽  
Francis J. P. Ebling
Keyword(s):  
Weight Control ◽  
Cell Function ◽  
High Growth ◽  
High Growth Rate ◽  
Nutrient Sensing ◽  
Surgical Approaches ◽  
Appetite Control ◽  
Annual Cycles ◽  
Seasonal Signals

Animal models are valuable for the study of complex behaviours and physiology such as the control of appetite because genetic, pharmacological and surgical approaches allow the investigation of underlying mechanisms. However, the majority of such studies are carried out in just two species, laboratory mice and rats. These conventional laboratory species have been intensely selected for high growth rate and fecundity, and have a high metabolic rate and short lifespan. These aspects limit their translational relevance for human appetite control. This review will consider the value of studies carried out in a seasonal species, the Siberian hamster, which shows natural photoperiod-regulated annual cycles in appetite, growth and fattening. Such studies reveal that this long-term control is not simply an adjustment of the known hypothalamic neuronal systems that control hunger and satiety in the short term. Long-term cyclicity is probably driven by hypothalamic tanycytes, glial cells that line the ventricular walls of the hypothalamus. These unique cells sense nutrients and metabolic hormones, integrate seasonal signals and effect plasticity of surrounding neural circuits through their function as a stem cell niche in the adult. Studies of glial cell function in the hypothalamus offer new potential for identifying central targets for appetite and body weight control amenable to dietary or pharmacological manipulation.

scholarly journals effectiveness of indigenous local microorganisms in degrading hexavalent chromium (Cr(VI)) in Batik liquid waste

2021 ◽  
Vol 1 (1) ◽  
pp. 19-29
Author(s):  
Reza Fauzi Dwisandi ◽  
Frista Mutiara ◽  
Elsa Nurfauziah ◽  
Vita Meylani
Keyword(s):  
Hexavalent Chromium ◽  
High Efficiency ◽  
Waste Treatment ◽  
Liquid Waste ◽  
High Growth ◽  
Textile Wastewater ◽  
High Growth Rate ◽  
Gram Negative Bacteria ◽  
Small And Medium Industry

The batik industry in Indonesia has an IKM (Small and Medium Industry) scale so that it does not yet have adequate waste treatment. In the long term, waste is disposed of directly into the environment which can damage aquatic ecosystems and harm human health. Textile wastewater has a complementary picture and has a deep color. One of the most dangerous heavy metals contained in textile waste is hexavalent chromium (Cr(VI)). Several ways can be done to reduce hexavalent chromium (Cr(VI)) by bioremediation. Based on the results of the literature review, it shows that the bioremediation agents from single isolate microorganisms that are most effective in degrading chromium with high efficiency are Bacillus subtilis and Pseudomonas aeruginosa. The most effective consortium servers with constant reduction rates are the consortium of bacteria genus Mesophilobacter, Methylococcus, Agrobacterium, Neisseria, Xanthobacter, Deinococcus, Sporosarcina, and Bacillus by reducing BOD levels by 85.71%. The hexavalent chromium-degrading microorganisms are characterized by the presence of chromate reductase enzymes, mostly gram-negative bacteria, and a high growth rate.

Oxidation Behavior of Stainless Steel with Electroless Ni-Fe-P Coatings

2010 ◽  
Vol 160-162 ◽  
pp. 1276-1279
Author(s):  
Shu Jiang Geng ◽  
Qian Wang
Keyword(s):  
Stainless Steel ◽  
Oxide Scale ◽  
Ferritic Stainless Steel ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Surface Oxide ◽  
Oxidation Time ◽  
Mass Ratio ◽  
Bare Steel ◽  
Electroless Ni

Ni-Fe-P coatings were deposited on ferritic stainless steel by means of electroless method. The oxidation behavior of the steel with these coatings were investigated at 800°C in air. The mass gain of the steel with Ni-Fe-P coatings deposited from solutions with different mass ratios of FeSO4 to NiSO4 decreased with increasing mass ratio. For the steel with Ni-Fe-P coating deposited in the solution with 0.25 of the mass ratio, the mass gain increased with the increase in oxidation time. While the mass gain of the steel with coatings deposited in solution with 0.5 and 0.75 of the mass ratio, respectively, became stable after 10-h oxidation. Compared with Ni-P, The Ni-Fe-P coatings improved the spallation resistance of the surface oxide scale. The oxide scale formed the bare steel consisted of Cr2O3 with TiO2 and (Mn,Cr)3O4 spinel. However, the oxide scale thermally grown on the steel with Ni-Fe-P coatings was composed of NiO, (Ni,Fe)3O4 spinel and Cr2O3.

scholarly journals Genetic Resource of Muscovy Duck (Cairina moschata): Profile and Potential Production as Meat Producer

2018 ◽  
Vol 28 (3) ◽  
pp. 129 ◽  
Author(s):  
Hasil Tamsil
Keyword(s):  
Egg Production ◽  
Genetic Resource ◽  
High Growth ◽  
High Growth Rate ◽  
Muscovy Duck ◽  
Short Term ◽  
Term Selection ◽  
Cairina Moschata

Muscovy duck is a type of waterfowl that has a relatively better growth and percentage compared to ducks. Duck meat has high-quality because of its low fat and savory flavor. Muscovy duck is relatively resistant to the disease and is able to use low-quality feed, but has the disadvantage of low egg production. The development of Muscovy duck as a producer of meat can be done through two approaches, namely the long-term and short-term. The long-term approach is carried out by selecting Muscovy duck which has high growth rate and high meet quality. The selection can be done in two ways, namely directly on the nature of growth and the quality of meat, and indirectly by choosing a marker of growth (morphology, biochemistry or diversity of DNA/ RNA). Short-term selection can be done by bringing in superior Muscovy duck from the outside to be developed by farmers and crossing male Muscovy duck with the layer Indian Runner ducks to produce Serati ducks.

Mechanical Properties and Adherence of Oxide Scales

2006 ◽  
Vol 522-523 ◽  
pp. 393-400 ◽  
Author(s):  
Michael Schütze ◽  
M. Malessa ◽  
Daniel Renusch ◽  
P.F. Tortorelli ◽  
Ian G. Wright ◽  
...  
Keyword(s):  
Oxide Scale ◽  
Laboratory Data ◽  
Computer Assisted ◽  
Failure Model ◽  
Scale Spallation ◽  
Macroscopic System ◽  
Temperature Oxidation ◽  
Adherence Scale ◽  
Critical Scale

In the high temperature oxidation of metallic alloys oxide scale strains and in particular critical scale strains play a key role with regard to scale adherence. Scale spallation/exfoliation is a vital issue for not only long term alloy performance but also steel sheet production. In many cases materials selection is based on thermodynamic considerations and short term laboratory data, not taking into account changes in the oxidation mechanisms resulting from stresses induced by thermal cycles, oxide growth, specimen or component geometry, or other operational factors. This paper presents a very concise summary of the present knowledge in the form of an approach to a comprehensive scale failure model which is based on a number of microscopic and macroscopic system parameters. This failure model is part of an on-going work which aims at a computer-assisted assessment of oxide scale mechanical reliability.

scholarly journals The Role Of Growth In Long Term Investment Returns

2011 ◽  
Vol 21 (1) ◽  
Author(s):  
John Paul Broussard ◽  
David Michayluk ◽  
Walter P. Neely
Keyword(s):  
Explanatory Power ◽  
High Growth ◽  
High Growth Rate ◽  
Investment Strategies ◽  
Growth Strategies ◽  
Stock Valuation ◽  
Holding Period ◽  
Investment Returns

<p class="MsoBodyText2" style="margin: 0in 0.5in 0pt;"><span style="font-size: 10pt;"><span style="font-family: Times New Roman;">Stocks with a high valuation compared to fundamental values imply a high growth rate, yet these stocks have typically under-performed in subsequent years supporting Lakonishok, Shleifer and Vishney's (1994) contrarian investment strategies. The precise definition of growth and subtle differences of measuring growth are explored in assessing the role of growth in long-term investment decisions and stock valuation.<span style="mso-spacerun: yes;">&nbsp; </span>Results from a later period and with additional tests than employed by LSV indicate that growth is a primary valuation factor, and valuation measures such as E/P and B/M, are imperfect proxies for expected growth.<span style="mso-spacerun: yes;">&nbsp; </span>Growth appears mean reverting, but investors do not seem able to discern changes in growth rates and this miss-specification of expected growth may help explain the superiority of value versus growth strategies. In addition, investors&rsquo; na&iuml;ve extrapolations of past growth provide explanatory power in future holding period returns.<span style="mso-spacerun: yes;">&nbsp; </span></span></span></p>

Effect of Pre-Oxidation on The Oxidation Behavior of Ti-2Al-2.5Zr Alloy at 300°C in An Alkaline Steam

2001 ◽  
Vol 697 ◽  
Author(s):  
X. T. Zu ◽  
Y. L. Li ◽  
G.T. Zeng ◽  
X. Q. Huang ◽  
Z.G. Wang ◽  
...  
Keyword(s):  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Deionized Water ◽  
Comparison Study ◽  
Oxide Scales ◽  
Water Steam ◽  
Result Analysis

AbstractThe long-term oxidation behavior on a Ti-2Al-2.5Zr alloy with and without pre-oxidation oxidized at 300 in an alkaline steam for about 13000h were studied. Some of the samples were subjected to 400°C deionized water steam at a pressure of 10MPa for 72 hours for pre-oxidation. A comparison study has been carried out between the pre-oxidized and without pre-oxidized Ti-2Al-2.5Zr to determine the influence of pre-oxidation upon the properties of oxidation resistance. The result analysis showed that the oxide scales on the Ti-2Al-2.5Zr alloy consisted of Al2TiO5, TiO2, Ti3O5, Ti2O3, Al2O3 and TiO. The oxidation kinetics showed that the weight gains of the pre-oxidized samples were much less than that of the without pre-oxidized samples. The AES results showed that the whole thickness of the pre-oxidized sample thinner than that of the without pre-oxidized one, in contrast the pattern for the stable oxide scale was reversed, i.e. the pre-oxidized sample was much thicker. It is thought that pre-oxidation is an effective method to enhance the oxidation resistance of Ti-2Al-2.5Zr.

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