Activation Energy for Recrystallization in Fe-3wt.%Si Alloys with Different S Contents

2013 ◽  
Vol 753 ◽  
pp. 181-184 ◽  
Author(s):  
Wei Min Mao ◽  
Mao Hua Zhang ◽  
Ping Yang ◽  
Kai Ping Wang
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Boundary Migration ◽  
Mechanical Calculation ◽  
High Temperature Range ◽  
Temperature Range ◽  
Cottrell Atmosphere

The recrystallization behaviors of 60% rolled Fe-wt.3%Si and Fe- wt.3%Si-Mn-S alloys containing coarsen MnS particles were observed in temperature range 600°C~1000°C. The activation energy for recrystallization was determined according to an Arrhenius type of relationship. It was found that the activation energy in the temperature range 600°C~750°C was much higher than that in the temperature range 850°C~1000°C. Thermo-mechanical calculation indicates that there are hardly precipitation behaviors of MnS particles in 600°C~1000°C. Fe3C will precipitate below 650°C and Cottrell atmosphere will form just above 650°C, which induces dragging effect against the boundary migration during recrystallization and increase the activation energy. The activation energy determined was about 99kJ/mol or 217kJ/mol in Fe-3%Si alloy and 91kJ/mol or 220kJ/mol in Fe-3%Si-Mn-S alloy for the recrystallization in high temperature range of 850°C~1000°C or low temperature range of 600°C~750°C respectively.

scholarly journals High-Temperature Deformation of Naturally Aged 7010 Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 581
Author(s):  
Abdulhakim A. Almajid
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Threshold Stress ◽  
Activation Energies ◽  
Temperature Deformation ◽  
High Temperature Range ◽  
Temperature Range ◽  
True Activation Energy ◽  
Two Temperatures

This study is focused on the deformation mechanism and behavior of naturally aged 7010 aluminum alloy at elevated temperatures. The specimens were naturally aged for 60 days to reach a saturated hardness state. High-temperature tensile tests for the naturally aged sample were conducted at different temperatures of 573, 623, 673, and 723 K at various strain rates ranging from 5 × 10−5 to 10−2 s−1. The dependency of stress on the strain rate showed a stress exponent, n, of ~6.5 for the low two temperatures and ~4.5 for the high two temperatures. The apparent activation energies of 290 and 165 kJ/mol are observed at the low, and high-temperature range, respectively. These values of activation energies are greater than those of solute/solvent self-diffusion. The stress exponents, n, and activation energy observed are rather high and this indicates the presence of threshold stress. This behavior occurred as a result of the dislocation interaction with the second phase particles that are existed in the alloy at the testing temperatures. The threshold stress decreases in an exponential manner as temperature increases. The true activation energy was computed by incorporating the threshold stress in the power-law relation between the stress and the strain. The magnitude of the true activation energy, Qt dropped to 234 and 102 kJ/mol at the low and high-temperature range, respectively. These values are close to that of diffusion of Zinc in Aluminum and diffusion of Magnesium in Aluminum, respectively. The Zener–Hollomon parameter for the alloy was developed as a function of effective stress. The data in each region (low and high-temperature region) coalescence in a segment line in each region.

scholarly journals A Study of Isothermal Curing of PMI Using DMA

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Jing Zhang ◽  
Rui Ye ◽  
Jun Zou ◽  
Jijun Tang ◽  
Hongliang Wang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Nonequilibrium Thermodynamic ◽  
Fluctuation Theory ◽  
Avrami Equation ◽  
High Temperature Range ◽  
Dynamic Mechanical ◽  
Temperature Range ◽  
Thermodynamic Fluctuation ◽  
Relative Conversion

The isothermal curing of polymethacrylimide (PMI) is studied through the use of dynamic mechanical analysis (DMA). Based on the growth rate of measured dynamic mechanical property, the relative conversion is defined to investigate the evolution of storage modulusE′at different curing temperatures. Hsich’s nonequilibrium thermodynamic fluctuation theory, Avrami equation, and isoconversional methods are used to analyze isothermal cure kinetics of PMI. The results show that there are different increase modes ofE′at low temperature range and high temperature range, respectively. In low temperature range, the relative conversion curves include a transitional stage which is found to be strongly frequency-dependent, but this stage is not observed in the relative conversion curve in high temperature range. During the isothermal curing process, the relative evolution ofE′can be described by Hsich’s nonequilibrium thermodynamic fluctuation theory and Avrami equation. Moreover, the values and evolutions of activation energy are different in two temperature ranges, which suggest that the curing mechanism probably has changed.

Linear red/green ratiometric thermometry of Ho3+/Cr3+ co-doped red up-conversion tungstate materials

2021 ◽  
Author(s):  
Yan Zhao ◽  
Xusheng Wang ◽  
Rui Hu ◽  
Yanxia Li
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Sensitivity ◽  
Temperature Sensing ◽  
High Temperature Range ◽  
Temperature Range ◽  
Co Doped ◽  
Sensing Performance

Existing optical thermometers are faced with the challenges of high sensitivity limited to a very narrow high temperature range, while also lacking low temperature sensing performance. A new linear up-conversion...

Semiconducting Molybdenum Pyrochlores for high Temperature Applications

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Low Temperature ◽  
Solid Solutions ◽  
Power Factor ◽  
Charge Carriers ◽  
Temperature Range ◽  
Maximum Power Factor ◽  
Increasing Temperature

ABSTRACTThe solid solutions (Y1-xYbx)2Mo2O7 were prepared and the systematic changes in the electrical resistivity (ρ=l/σ), thermopower (S) and power factor (S2σ) have been studied in the temperature range 300–900 K. The lattice parameters ‘a’ and ‘c’ are smaller for higher Yb3+ content phases due to smaller Yb3+ radius and a small tetragonality is observed for all the phases. Semiconducting behaviour is seen for all compositions with systematic increase in activation energy with increasing Yb content. All compositions show negative thermopower indicating electrons are the majority charge carriers in the temperature range of measurements. The calculated power factor values S2σ increase with increasing temperature in the low temperature region and a maximum power factor of ∼0.76×10−7 Wcm−1K−2 is observed at 650K.

Analysis of Temperature Characteristics of an AlGaAs/GaAs/Ge Triple-Junction Solar Cell by IS

2013 ◽  
Vol 756-759 ◽  
pp. 101-104
Author(s):  
Yi Qing Zhang ◽  
Wen Jun Cao ◽  
Ai Min Liu
Keyword(s):  
Solar Cell ◽  
High Temperature ◽  
Impedance Spectroscopy ◽  
Low Temperature ◽  
Equivalent Circuit ◽  
Triple Junction ◽  
Temperature Characteristics ◽  
High Temperature Range ◽  
Temperature Range ◽  
Junction Solar Cell

Composition of an AlGaAs/GaAs/Ge triple-junction solar cell were analyzed using an equivalent circuit. The currentvoltage (IV) characteristics and impedance spectroscopy (IS) of it were measured in the temperature range from 20°C to 180°C. In the high-temperature range (from 140°C to 200°C) the VOCchanges faster than those in the low-temperature range (from 20°C to 80°C).This is because contribution of the VOCfrom the Ge subcell becomes nearly zero in the high temperature. R and C of the bottom subcell keep almost the same in the high temperature.

Method for extending the scale of a radiation pyrometer to the high-temperature range

1965 ◽  
Vol 8 (10) ◽  
pp. 963-965
Author(s):  
L. M. Golub ◽  
V. E. Finkel'shtein ◽  
E. S. Shpigel'man
Keyword(s):  
High Temperature ◽  
Radiation Pyrometer ◽  
High Temperature Range ◽  
Temperature Range

Defect Assessment Procedure for Low to High Temperature Range

2003 ◽  
Author(s):  
Bilal Dogan ◽  
Robert Ainsworth
Keyword(s):  
High Temperature ◽  
Growth Conditions ◽  
Life Assessment ◽  
Assessment Procedure ◽  
High Temperature Range ◽  
Temperature Range ◽  
Defect Assessment ◽  
Creep Fatigue ◽  
Recent Developments ◽  
Assessment Procedures

There are many similarities between available procedures used for defect assessment. They have been developed as a result of experience gained from material-specific programs and have often been verified using the same data. One recently updated document covering life assessment procedures under creep and creep/fatigue crack growth conditions is BS 7910. This document takes into account some of the most recent developments in the subject, including some from the British Energy R5 Procedure. Future developments in defect assessment procedures will follow the route of simplified and unified codes covering defect behaviour in the low to high temperature range. In this paper, the relevance of the insignificant creep curves in RCC-MR for defect free structures and the creep exemption criteria in BS7910 are examined. Then, an overview is given of some European developments in defect assessment methods for Fitness-for-Service assessment, based on recent and current projects such as the EC thematic network FITNET.

Basic Experiment on Lithium Removal Technique

2012 ◽  
Author(s):  
Tomohiro Furukawa ◽  
Yasushi Hirakawa
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Dissolution Rate ◽  
Chemical Reaction ◽  
Pure Water ◽  
Preliminary Investigation ◽  
Testing Temperature ◽  
Temperature Range ◽  
Removal Technique ◽  
Good Agreement

As a preliminary investigation into the establishment of a lithium removal technique for the components used at the International Fusion Materials Irradiation Facility (IFMIF), experiments were performed on the dissolution of lithium in three solvents: ethanol, pure water, and ethanol–water. In these experiments, hemispherical lithium was immersed in the solvents at constant temperatures, and the degree of dissolution was measured continuously from the height of the sample. From the obtained data, the average dissolution rate in the solvents at each testing temperature (10–90 °C) and the amount of hydrogen generated by the chemical reaction were calculated. The average dissolution rates in ethanol, pure water, and ethanol–water at 30 °C were 0.01, 1.6, and 0.43 mm/min, respectively. Although the average dissolution rate increased with the testing temperature in the low-temperature range (10–50 °C) for all solvents, this increase was saturated in the high-temperature range (50–90 °C) in experiments with pure water and ethanol–water as solvents. The volume of gas collected during each experiment was in good agreement with the volume of hydrogen assumed to be generated from the chemical reaction of lithium with the solvents.

Development of Red Mud Coated Catalytic Filter for NOx Removal in the High Temperature Range of 300–450 °C

2019 ◽  
Vol 150 (3) ◽  
pp. 702-712 ◽  
Author(s):  
Lin Huangfu ◽  
Abdullahi Abubakar ◽  
Changming Li ◽  
Yunjia Li ◽  
Chao Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Red Mud ◽  
Nox Removal ◽  
High Temperature Range ◽  
Temperature Range ◽  
Catalytic Filter
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