Development of high temperature creep resistance in Fe-Al alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
D. G. Morris ◽  
M. A. Muñoz-Morris ◽  
C. Baudin
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Creep Resistance ◽  
Good Strength ◽  
Thermally Activated ◽  
Intermediate Temperature Range ◽  
Deformation Processes ◽  
Good Creep Resistance ◽  
Oxidation And Corrosion ◽  
Very High

ABSTRACTMost of the studies aimed at the development of creep-resisting Fe-Al intermetallics have been oriented at application temperatures of the order of 500–650°C, where these materials may compete with conventional stainless steels. The Fe-Al intermetallics are, however, particularly excellent in their oxidation and corrosion resistances at temperatures of the order of 1000°C, where Chromium-Nickel steels are no longer able to withstand the aggressive environments. This presentation is part of a study aimed at the development of good creep resistance at such high temperatures.Studies of a variety of cast Fe3Al-base alloys, strengthened by solution or precipitate/dispersoid-forming alloying additions, are reported. The alloys show good strength from room temperature to about 500°C, but thereafter strength falls rapidly as thermally-activated deformation processes become operative. Solution additions are capable of producing good low temperature strength, but do not contribute significantly to creep strength at very high temperatures (above 700°C). Precipitation hardening has been examined in Nb-containing alloys, where Fe2Nb Laves precipitates form at intermediate temperatures. These materials show good strength up to about 700°C, but at higher temperatures the fine precipitates coarsen excessively. Strengthening in the intermediate temperature range varies depending on whether the solute is precipitated prior to high temperature testing or concurrent with this.

KUBOTA UCX

Alloy Digest ◽  
2008 ◽  
Vol 57 (6) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Temperature Performance ◽  
High Temperature Operation ◽  
Oxidation And Corrosion ◽  
Very High

Abstract Kubota UCX was developed for very high temperature operation for ethylene pyrolysis service. The alloy also has excellent oxidation and corrosion resistance. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as casting and joining. Filing Code: Ni-663. Producer or source: Kubota Metal Corporation, Fahramet Division.

Characteristics and aging of SiC MOSFETs operated at very high temperatures

2014 ◽  
Vol 1693 ◽  
Author(s):  
Dean P. Hamilton ◽  
Michael R. Jennings ◽  
Craig A. Fisher ◽  
Yogesh K. Sharma ◽  
Stephen J. York ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Threshold Voltage ◽  
Thermal Aging ◽  
Ohmic Contacts ◽  
Stress Tests ◽  
Temperature Capability ◽  
Temperature Constant ◽  
Voltage Management ◽  
Very High

ABSTRACTSilicon carbide power devices are purported to be capable of operating at very high temperatures. Current commercially available SiC MOSFETs from a number of manufacturers have been evaluated to understand and quantify the aging processes and temperature dependencies that occur when operated up to 350°C. High temperature constant positive bias stress tests demonstrated a two times increase in threshold voltage from the original value for some device types, which was maintained indefinitely but could be corrected with a long negative gate bias. The threshold voltages were found to decrease close to zero and the on-state resistances increased quite linearly to approximately five or six times their room temperature values. Long term thermal aging of the dies appears to demonstrate possible degradation of the ohmic contacts. This appears as a rectifying response in the I-V curves at low drain-source bias. The high temperature capability of the latest generations of these devices has been proven independently; provided that threshold voltage management is implemented, the devices are capable of being operated and are free from the effects of thermal aging for at least 70 hours cumulative at 300°C.

scholarly journals Forging, textures, and deformation systems in a B2 FeAl alloy

1999 ◽  
Vol 14 (3) ◽  
pp. 715-728 ◽  
Author(s):  
P. Zhao ◽  
D. G. Morris ◽  
M. A. Morris Munoz
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Slip System ◽  
High Temperatures ◽  
Low Temperatures ◽  
High Speed ◽  
Deformation Texture ◽  
Slip Systems ◽  
Feal Alloy ◽  
Very High

High-temperature forging experiments have been carried out by axial compression testing on a Fe–41Al–2Cr alloy in order to determine the deformation systems operating under such high-speed, high-temperature conditions, and to examine the textures produced by such deformation and during subsequent annealing to recrystallize. Deformation is deduced to take place by the operation of 〈111〉 {110} and 〈111〉{112} slip systems at low temperatures and by 〈100〉{001} and 〈100〉{011} slip systems at high temperatures, with the formation of the expected strong 〈111〉 textures. The examination of the weak 〈100〉 texture component is critical to distinguishing the operating slip system. Both texture and dislocation analyses are consistent with the operation of these deformation systems. Recrystallization takes place extremely quickly at high temperatures (above 800 °C), that is within seconds after deformation and also dynamically during deformation itself. Recrystallization changes the texture such that 〈100〉 textures superimpose on the deformation texture. The flow stress peak observed during forging is found at a very high temperature. Possible origins of the peak are examined in terms of the operating slip systems.

Integrity assessment of the high temperature engineering test reactor (HTTR) control rod at very high temperatures

1997 ◽  
Vol 172 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
Y. Tachibana ◽  
S. Shiozawa ◽  
J. Fukakura ◽  
F. Matsumoto ◽  
T. Araki
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Control Rod ◽  
Integrity Assessment ◽  
Test Reactor ◽  
Very High

Applications: Light My Fire

1982 ◽  
Vol 75 (1) ◽  
pp. 53-55
Author(s):  
George Knill ◽  
George Fawceti
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Low Temperatures ◽  
Chemical Process ◽  
Room Temperature ◽  
Very High

Everyone knows that wood bums at a very high temperature. This burning is a chemical process that combines oxygen and carbon. The process occurs at very low temperatures as well as at very high ones. At high temperatures the process is spectacular-fire. At low temperatures (room temperature) you won’t even notice it, although it is still going on. Wood is always burning.

High Temperature Thermoelectric Properties of Boron Carbide

1991 ◽  
Vol 234 ◽  
Author(s):  
T. L. Aselage
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermoelectric Properties ◽  
Power Conversion ◽  
Unusual Structure ◽  
Thermally Activated ◽  
Structure And Bonding ◽  
Increasing Temperature ◽  
P Type ◽  
Very High

ABSTRACTBoron carbides are refractory solids with potential for application as very high temperature p-type thermoelectrics in power conversion applications. The thermoelectric properties of boron carbides are unconventional. In particular, the electrical conductivity is consistent with the thermally activated hopping of a high density (≈ 1021/cm3) of bipolarons; the Seebeck coefficient is anomalously large and increases with increasing temperature; and the thermal conductivity is surprisingly low. In this paper, these unusual properties and their relationship to the unusual structure and bonding present in boron carbides are reviewed. Finally, the potential for utilization of boron carbides at very high temperatures (up to 2200°C) and for preparing n-type materials is discussed.

In-situ Hrem Heating Experiments at Very High Temperatures

1995 ◽  
Vol 404 ◽  
Author(s):  
T. Kamino ◽  
H. Saka
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Atomic Resolution ◽  
Very High

AbstractA specimen-heating holder which allows an observation of reactions of more than one materials, in a controlled manner, at such a high temperature as 1723K has been developed. Facet-unfacet transformation and reconstruction of Au-deposited Si surfaces have been observed at very high temperatures at near-atomic resolution.

COLUMBIUM D-31

Alloy Digest ◽  
1963 ◽  
Vol 12 (3) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
High Temperatures ◽  
Base Alloy ◽  
Density Ratio ◽  
Heat Treating ◽  
Temperature Performance ◽  
Very High

Abstract COLUMBIUM D-31 is a columbium-base alloy that maintains its stability at very high temperatures. It is 5 times as resistant to oxidation as pure columbium and about 100 times as resistant as molybdenum. Its strength to density ratio at 2000 F (stress relieved) is 77400. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-4. Producer or source: E. I. Dupont de Nemours & Company Inc..

Biodegradation of aliphatic and aromatic hydrocarbons at high temperatures

2003 ◽  
Vol 47 (10) ◽  
pp. 123-130 ◽  
Author(s):  
H. Feitkenhauer ◽  
H. Märkl
Keyword(s):  
High Temperature ◽  
Kinetic Parameters ◽  
Mixed Culture ◽  
High Temperatures ◽  
Aromatic Hydrocarbons ◽  
Chemical System ◽  
Separate Experiment ◽  
Phenol Biodegradation ◽  
Aliphatic And Aromatic Hydrocarbons ◽  
Very High

In this paper, the high temperature (65-75°C) biodegradation of aliphatic and aromatic hydrocarbons is investigated and kinetic parameters are derived. The shift of the physico-chemical system properties with rising temperature will be discussed in detail. For example, the solubility of naphthalene is increased by a factor of about ten if the temperature is increased from 20 to 75°C. This effect is essential to increase the bioavailability of sparingly soluble hydrocarbons. It is also demonstrated in experiments that very high oxygen transfer rates can be obtained at high temperatures in the presence of hydrocarbons. It is shown that efficient phenol biodegradation is essential for high temperature hydrocarbon degradation because some microorganisms tend to transform phenols into polyphenols which are very inhibitory for microbial growth. A defined mixed culture adapted to phenol converted more than 90% of a mixture of phenol, hexadecane and pyrene and a very high maximal growth rate of 0.19 h−1 was determined. A yield coefficient YX/S of about 0.8 g (biomass)/g (hydrocarbons) was calculated in this experiment. In a separate experiment the influence of the hydrocarbon droplet size on the biodegradation is investigated at 70°C using a newly isolated Thermus sp. In this case, the growth on a hexadecane/pyrene mixture was described by a model based on the Monod equation and the corresponding kinetic parameters are derived. A mixed culture was used for the bioremediation of soil in a slurry reactor. The initial contamination of 11 g/kg was lowered to about 2 g in a reactor inoculated by an immobilized culture of extreme thermophilic microorganisms, while 9 g/kg remained in a sterile control.

High-temperature survival is limited by food availability in first-instar locust nymphs

2010 ◽  
Vol 58 (5) ◽  
pp. 323 ◽  
Author(s):  
James D. Woodman
Keyword(s):  
High Temperature ◽  
Food Availability ◽  
High Temperatures ◽  
Water Loss ◽  
Local Population ◽  
Maximum Temperature ◽  
Upper Limit ◽  
First Instar ◽  
Low Humidity ◽  
Very High

The Australian plague locust, Chortoicetes terminifera (Walker), is often exposed to high temperature and low humidity in semiarid and arid environments. Early-instar survival under these conditions is an important prerequisite for the formation of high-density aggregations in summer and autumn generations. The present study investigates how first-instar C. terminifera respond to high temperature and low humidity using measures of total body water content, physiological and behavioural transitions during temperature increase, critical upper limit, and mortality relative to food availability. The critical upper limit for fed nymphs was very high at 53.3 ± 1.0°C, with death preceded by a clear progression of changes in behaviour, gas exchange, water loss and excretion. At more ecologically relevant high temperatures, food availability allowed nymphs to behaviourally respond to increased water loss, and the resulting physiological maintenance of water reserves provided cross-tolerance to heat relative to exposure duration and maximum temperature as well as the rate of warming. While very high mortality was recorded at ≥45°C in 6-h direct-exposure experiments, a highly exposed and very poorly vegetated summer environment would be required for local population failures from current high temperatures and low humidity alone.

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