Controlling the Microstructure of the 2223 Phase Grains for the Fabrication of Silver Clad (Bi,Pb)2Sr2Ca2Cu3Ox Tapes Through the Growth Kinetics of the Superconducting Phases

1992 ◽  
Vol 275 ◽  
Author(s):  
Wai Lo ◽  
B. A. Glowacki
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Liquid Phase ◽  
Bulk Density ◽  
Growth Kinetics ◽  
Major Phase ◽  
Average Grain Size ◽  
The Relationship ◽  
Kinetics Of ◽  
Fast Growth Rate

ABSTRACTOur study concentrated on the relationship between the proportions of the phases in the precursors used to synthesise the Bi-2223 phase and the ultimate microstructures of the 2223 phase materials, although the overall cation stoichiometry fixed. It was found that the final 2223 phase grains were larger, although the bulk density tended to be lower with the grains loosely packed together, when the major phase in the precursor was 2212 phase. This was proved to be partly caused by the fast growth rate of the 2212 phase grains which were eventually converted into the 2223 phase. When 2223 phase was present in the precursor, the bulk density became higher and 2223 phase grains became closely packed together, although the average grain size became smaller. This was explained by the existence of a liquid phase at higher temperatures during the formation of the 2223 phase and the sintering of the 2223 phase grains.

Growth Kinetics and Formation of Uniform Self-Assembled InAs/GaAs Quantum Dots at

2007 ◽  
Vol 124-126 ◽  
pp. 539-542
Author(s):  
Eui Tae Kim ◽  
Anupam Madhukar
Keyword(s):  
Growth Rate ◽  
Quantum Dots ◽  
Growth Kinetics ◽  
Slow Growth ◽  
Fast Growth ◽  
Slow Growth Rate ◽  
Self Assembled ◽  
Kinetics Of ◽  
Fast Growth Rate ◽  
2D To 3D

We discuss the growth kinetics of InAs/GaAs self-assembled quantum dots (QDs) using two different InAs deposition rates, relatively fast growth rate of 0.22 ML/sec and slow growth rate of 0.054 ML/sec. With increasing InAs deposition amount to 3.0 ML, the QD density was almost constant after 2D to 3D island transition at the slow deposition rate while the QD density kept increasing and the QD size distribution was relatively broad at the fast growth rate. After the 2D to 3D transition, at the slow growth rate, further deposited In adatoms seemed to incorporate primarily into already formed islands, and thus contribute to equalize island size. The photoluminescence (PL) full-width at half maximum (FWHM) of 2.5 ML InAs QDs at 0.054 ML/sec was 23 meV at 78K. The PL characteristics of InAs/GaAs QDs were degraded significantly after thermal annealing at 550 oC for 3 hours.

Physical Quality of Turmeric Powder (Curcuma longga Linn) Result of Foam-mat Drying Method Using Microwave

2021 ◽  
pp. 57-65
Author(s):  
Dhinar Patliani ◽  
Dian Purbasari
Keyword(s):  
Grain Size ◽  
Moisture Content ◽  
Water Absorption ◽  
Bulk Density ◽  
Oil Absorption ◽  
Drying Method ◽  
Physical Quality ◽  
Average Grain Size ◽  
Two Factors

Turmeric (Curcuma longa L) in Indonesia is widely known as a herbal medicinal plant, food coloring, and food flavoring. The high water content of turmeric will shorten the storage time and the quality of the ingredients. The need for drying which is the process of removing the moisture content of the material with the aim of prolonging the shelf life. The use of the foam-mat drying method with the addition of adhesives aims to speed up the drying process and maintain the quality of a material. The result of drying turmeric obtained is turmeric powder product. This study used a completely randomized design (CRD) with two factors, namely the variation of the microwave oven power and the composition of the developer agent (ovalet). The research procedure was divided into two stages, namely the manufacture of powder and continued with the measurement of physical quality. The stages of making powder begin with the preparation of raw materials, stripping, size reduction, addition of developer, drying, then grinding. The second stage is measuring physical quality, namely fineness modulus, average grain size, powder moisture content, color, water absorption, oil absorption, and bulk density. The power variations used are 420 watts, 535 watts, and 680 watts, while the composition of the developer is 1%, 2%, and 4%. Data analysis using two-way ANOVA statistical test with two factors that affect the variation of power and composition of the developer (ovalet). FM values ​​ranged from 0.364 – 1.576, D values ​​ranged from 0.005 – 0.0012 mm, final moisture content values ​​ranged from 7.60 – 9.59%, powder moisture content values ​​ranged from 9.47 – 11.43%ww , L values ​​ranged from 61.46 – 65.96, a values ​​ranged from 13.54 – 16.05, b values ​​ranged from 48.21 – 52.42, DSA values ​​ranged from 2.78 – 3.54 ml/ g, DSM values ​​ranged from 1.22 – 1.60 ml/g, and DC values ​​ranged from 0.38 – 0.44 g/cm3. The combination treatment of drying power with developer is influenced by the drying power of the parameters, namely the value of moisture content, fineness modulus, average grain size, brightness level, redness level, yellowness level, oil absorption, water absorption, and bulk density. While the developer affects the finenes modulus, average grain size, yellowness level, and bulk density.

Refinement of Size Distributions for Primary Crystallizations

1997 ◽  
Vol 481 ◽  
Author(s):  
E. Pineda ◽  
T. Pradell ◽  
D. Crespo ◽  
N. Clavaguera ◽  
J. ZHU ◽  
...  
Keyword(s):  
Grain Size ◽  
Metastable Phase ◽  
Primary Crystallization ◽  
Controlled Growth ◽  
Diffusion Controlled ◽  
Average Grain Size ◽  
Soft Impingement ◽  
Single Grain ◽  
Kinetics Of ◽  
And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

Low temperature sintering of nano-SiC using a novel Al8B4C7 additive

2010 ◽  
Vol 25 (3) ◽  
pp. 471-475 ◽  
Author(s):  
Sea-Hoon Lee ◽  
Byung-Nam Kim ◽  
Hidehiko Tanaka
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
Liquid Phase Sintering ◽  
Low Temperature Sintering ◽  
Densification Rate ◽  
Sintering Additive ◽  
Average Grain Size

Al8B4C7 was used as a sintering additive for the densification of nano-SiC powder. The average grain size was approximately 70 nm after sintering SiC-12.5wt% Al8B4C7 at 1550 °C. The densification rate strongly depended on the sintering temperature and the applied pressure. The rearrangement of SiC particles occurred at the initial shrinkage, while viscous flow and liquid phase sintering became important at the middle and final stage of densification.

Growth Kinetics of Interfacial Intermetallic Compound in Al(AA4343)/Steel(SUS316) Clad Strip

2020 ◽  
Vol 993 ◽  
pp. 447-456
Author(s):  
Xiao Jun Zhang ◽  
Kun Yuan Gao ◽  
Xiu Hua Hu ◽  
Yu Sheng Ding ◽  
Guo Zhan Wang ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Annealing Temperature ◽  
Optical Microscope ◽  
Alloy Layer ◽  
Kinetics Analysis ◽  
Growth Constant ◽  
Transmission Electron ◽  
Dispersive System ◽  
The Relationship ◽  
Kinetics Of

The composition and microstructure of intermetallic compounds (IMC) at the interface of aluminum(AA4343)-stainless steel(SUS316) were studied upon annealing at 550°C for 1h to 20h and at 610°C for 15min to 10h by means of optical microscope(OM) , scanning electron microscope (SEM) with energy dispersive system(EDS) and transmission Electron Microscopy (TEM). The results showed that the IMC was of 4.3μm to 36.1μm thick during heat treatment at 550°C for 1h to 20h, and the IMC contained Al-Fe-Si-Cr-Ni-Mo and Al-Fe-Si -Ni. During annealing at 610°C for 15min to 5h, the thickness of IMC was 31.2 μm to 208 μm, and the IMC were mainly of η-Fe2Al5 and τ10- Al4Fe1.7Si at 550°C for 10h. As the annealing time extended to 10h, natural delamination occurred at the interface between the aluminum alloy layer and IMC layer. The growth kinetics analysis showed that the relationship between the thickness of IMC “X” and time “t” followed the relational equation X=(kt)n. For AA4343(solid) - SUS316(solid), n was 1/2, and the growth constant k = 1.9×10-13m2/s at annealing temperature of 550 °C. When the temperature was 610°C, AA4343 - SUS316 was a liquid-solid contact reaction, n was 1, the growth constant k=1.45×10-8m/s.

Effect of rate controlled sintering on microstructure and electrical properties of ZnO doped with bismuth and antimony oxides

1997 ◽  
Vol 12 (9) ◽  
pp. 2447-2454 ◽  
Author(s):  
Gaurav Agarwal ◽  
Robert F. Speyer
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Second Phase ◽  
Dopant Content ◽  
Average Grain Size ◽  
Rate Controlled ◽  
Grain Boundary Pinning

Various rate controlled sintering (RCS) schedules were used on isostatically pressed particulate compacts of ZnO with Bi2O3 and Sb2O3 additives. For low additive content, smaller average grain sizes with more rapid RCS schedules were attributable to thermal schedules which minimized the time at elevated temperatures where grain growth could occur. β–Bi2O3, Zn7Sb2O12, and Zn2Sb3Bi3O14 phases formed during/after sintering. Elevated heat-treatment temperatures favored the formation of Zn7Sb2O12 and additional β–Bi2O3, while Zn2Sb3Bi3O14 was dominant in sintered samples where the RCS schedule did not result in temperatures in excess of 1100 °C. Zn2Sb3Bi3O14 precipitated during sintering, functioning as grain boundary pinning sites which impeded ZnO grain growth. Bismuth and antimony oxide-based liquid facilitated sintering at lower temperatures, which in turn resulted in decreased average grain size. Rapid RCS schedules for samples with low dopant content resulted in lower sintering temperatures, since time was not allowed for Zn2Sb3Bi3O14 precipitation to deplete the liquid phase. For higher dopant contents, liquid phase was adequately plentiful, wherein longer RCS schedules resulted in lower sintering temperatures. Increasing concentration of second phase generally fostered decreased grain size and attenuated the effect of thermal schedule on the microstructure. Electrical resistance and breakdown voltage increased consistent with decreasing ZnO average grain size.

Microstructure Prediction by Finite Element Analysis during Hot Rolling of Magnesium Alloy Sheets

2015 ◽  
Vol 661 ◽  
pp. 105-112
Author(s):  
Yeong Maw Hwang ◽  
Tso Lun Yeh
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Optimal Conditions ◽  
Compression Tests ◽  
Element Analysis ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Microstructure Prediction ◽  
Alloy Microstructure ◽  
The Relationship

Material’s plastic deformation by hot forming processes can be used to make the materials generate dynamic recrystallization (DRX) and fine grains and accordingly products with more excellent mechanical properties, such as higher strength and larger elongation can be obtained. In this study, compression tests and water quenching are conducted to obtain the flow stress of the materials and the grain size after DRX. Through the regression analysis, prediction equations for the magnesium alloy microstructure were established. Simulations with different rolling parameters are conducted to find out the relationship between the DRX fractions or grain sizes of the rolled products and the rolling parameters. The simulation results show that rolling temperature of 400°C and thickness reduction of 50% are the optimal conditions. An average grain size of 0.204μm-0.206μm in the microstructure is obtained and the strength and formability of ZK60 magnesium alloys can be improved.

scholarly journals Comparison of the Microstructure of M2 Steel Fabricated by Continuous Casting and with a Sand Mould

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 560
Author(s):  
Jinwen Zhang ◽  
Zhigang Zhao ◽  
Wenxian Wang ◽  
Yutian Wang
Keyword(s):  
Grain Size ◽  
Continuous Casting ◽  
Cooling Rate ◽  
Continuous Caster ◽  
Casting Process ◽  
Sand Mold ◽  
Average Grain Size ◽  
Kg Medium ◽  
The Relationship ◽  
Continuous Casting Billet

AISI M2 steel was smelted in a 150 kg medium-frequency induction furnace and cast to form round billets with a cross-section diameter of 100 mm via a vertical continuous caster and sand mold. The secondary dendrite arm spacing (λ2), cooling rates, permeability and size and distribution of grains and network carbides of the two billets were studied. The results show that the continuous casting process can effectively decrease the λ2 value, permeability and size of the grains and carbides and improve the distribution of the grains and carbides during solidification. The λ2 values of the billets cast with a sand mold and continuous caster are 37.34 μm and 21.14 μm, respectively, and the cooling rate is 3.6 K·s−1 and 12.0 K·s−1, respectively. The area fractions of carbides at the center of the billets cast with the sand mold and continuous caster are 0.24 and 0.16, respectively, and increase by 27.7% and 25.4%, respectively, compared with their average values. The average grain size of billets cast with the sand mold and continuous caster is 69.4 μm and 50.5 μm, respectively. Compared with the sand mold billet, the grain size at the center of the continuous casting billet is reduced by 25.5%. The relationship between the grain size and cooling rate is presented in this paper.

The Effect of Grain Size Distribution on the Mechanical Properties of Nanometals

2008 ◽  
Vol 140 ◽  
pp. 185-190 ◽  
Author(s):  
T.B. Tengen ◽  
Tomasz Wejrzanowski ◽  
R. Iwankiewicz ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flow Stress ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Deformation Mechanisms ◽  
Average Grain Size ◽  
Significant Interest ◽  
Size Dispersion ◽  
The Relationship

Predicting the properties of a material from knowledge of the internal microstructures is attracting significant interest in the fields of materials design and engineering. The most commonly used expression, known as Hall-Petch Relationship (HPR), reports on the relationship between the flow stress and the average grain size. However, there is much evidence that other statistical information that the grain size distribution in materials may have significant impact on the mechanical properties. These could even be more pronounced in the case of grains of the nanometer size, where the HPR is no longer valid and the Reverse-HPR is more applicable. This paper proposes a statistical model for the relationship between flow stress and grain size distribution. The model considered different deformation mechanisms and was used to predict mechanical properties of aluminium and copper. The results obtained with the model shows that the dispersion of grain size distribution plays an important role in the design of desirable mechanical properties. In particular, it was found that that the dependence of a material’s mechanical properties on grain size dispersion also follows the HPR to Inverse-HPR type of behaviour. The results also show that copper is more sensitive to changes in grain size distribution than aluminium.

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