Relaxation and Grain Growth Behavior of Nanocrystalline Iron

1992 ◽  
Vol 272 ◽  
Author(s):  
J. C. Holzer ◽  
R. Birringer ◽  
J. Eckert ◽  
C.E. Krill ◽  
W.L. Johnson
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Peak Broadening ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Nanocrystalline Iron ◽  
Grain Growth Behavior ◽  
Kinetics Of

ABSTRACTNanocrystalline Fe has been prepared by inert gas condensation and ball milling. The kinetics of relaxation and grain growth are investigated by differential scanning calorimetry. The development of the microstructure is monitored by x-ray powder diffraction and transmission electron microscopy. Emphasis is placed on the differences observed for samples prepared by the two different techniques. We find that the kinetics of relaxation and grain growth are very sensitive to the sample preparation method. Samples with the same initial average grain size, as determined by the peak broadening in x-ray diffraction, show very different recovery behavior. The differences are discussed in terms of the estimated grain boundary energies and the initial grain size distribution obtained by the two preparation techniques.

Grain-Growth Kinetics of Nanocrystalline Iron Studied In Situ by Synchrotron Real-Time X-ray Diffraction

2000 ◽  
Vol 104 (11) ◽  
pp. 2467-2476 ◽  
Author(s):  
H. Natter ◽  
M. Schmelzer ◽  
M.-S Löffler ◽  
C. E. Krill ◽  
A. Fitch ◽  
...  
Keyword(s):  
Real Time ◽  
Grain Growth ◽  
Growth Kinetics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanocrystalline Iron ◽  
Grain Growth Kinetics ◽  
Kinetics Of

Grain Size Dependent Magnetic Properties of Nanocrystalline Sm [BE]Co [BD][BJ]/Cu

2001 ◽  
Vol 703 ◽  
Author(s):  
L. Bessais ◽  
C. Djéga-Mariadassou ◽  
J. Zhang ◽  
V. Lalanne ◽  
A. Percheron-Guégan
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Magnetic Metal ◽  
Chemical Distribution

ABSTRACTThe evolution of both micro structural and magnetic properties of the Sm[BE]Co[BD][BJ] Cu powder, is studied as a function of soft co-milling time. The average grain size in the range 20 - 50 nm was determined by transmission electron microscopy coupled with x-ray diffraction using the Rietveld method. The particle shape and chemical distribution were investigated by elemental mapping, using wavelength dispersive x-ray analysis with electron microprobe analysis. The coercivity evolution shows that an optimum value of 6 kOe is obtained after 5 h co-milling. The microstructure analysis indicates that both materials are well mixed in nanometer scale. This technique appears as a potential route to synthesize nanocrystalline Sm[BE]Co[BD][BJ] isolated by non-magnetic metal Cu.

Characterization of Nanocrystalline γ–Fe2O3Prepared by Wet Chemical Method

1999 ◽  
Vol 14 (4) ◽  
pp. 1570-1575 ◽  
Author(s):  
G. Ennas ◽  
G. Marongiu ◽  
A. Musinu ◽  
A. Falqui ◽  
P. Ballirano ◽  
...  
Keyword(s):  
Isothermal Treatment ◽  
X Ray Diffraction ◽  
Ferrous Chloride ◽  
Scanning Calorimetry ◽  
Direct Transformation ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Kinetics Of

Homogeneous maghemite (γ–Fe2O3) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (α–Fe2O3), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 °C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.

Chemically disordered Ni3Al synthesized by high vacuum evaporation

1991 ◽  
Vol 6 (10) ◽  
pp. 2019-2021 ◽  
Author(s):  
S.R. Harris ◽  
D.H. Pearson ◽  
C.M. Garland ◽  
B. Fultz
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
High Vacuum ◽  
Liquid Nitrogen Temperature ◽  
Vacuum Evaporation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size

Films of chemically disordered fcc Ni3Al were synthesized by the vacuum evaporation of Ni3Al onto room temperature and liquid nitrogen temperature substrates. X-ray diffractometry and transmission electron microscopy showed the material to be single phase with an average grain size of about 4 nm. The formation of the equilibrium L12 ordered phase occurred simultaneously with grain growth at temperatures above 350°C. Differential scanning calorimetry provided ordering enthalpies of 7 kJ/mole and 9 kJ/mole for material evaporated onto room temperature and liquid nitrogen temperature substrates, respectively.

High grain size stability of nanocrystalline Al prepared by mechanical attrition

2001 ◽  
Vol 16 (12) ◽  
pp. 3451-3458 ◽  
Author(s):  
F. Zhou ◽  
J. Lee ◽  
S. Dallek ◽  
E. J. Lavernia
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermally Activated ◽  
Transmission Electron ◽  
Mechanical Attrition ◽  
Size Stability ◽  
Grain Growth Kinetics ◽  
Grain Size Stability

Grain growth in nanocrystalline (nc) Al with a grain size of 26 nm produced by cryogenic mechanical milling was studied through x-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. Grain growth kinetics resembled those of ball-milled nc Fe. For homologous temperatures (T/TM) of 0.51–0.83, the time exponent n from D1/n − D01/n = kt was 0.04–0.28, tending toward 0.5 as T/TM increased. Two grain-growth regimes were distinguished: below T/TM = 0.78 growth ceased at an approximate grain size of 50 nm while at higher temperatures, grain growth proceeded steadily to the submicrometer range. Grain growth over the range of temperatures studied cannot be explained in terms of a single thermally activated rate process. The observed high grain size stability was attributed primarily to impurity pinning drag associated with the grain growth process.

Nucleation and Grain Growth Kinetics of Amorphous to Nanocrystalline Ceria Solid Solutions

2007 ◽  
Vol 558-559 ◽  
pp. 1339-1344 ◽  
Author(s):  
Jennifer L.M. Rupp ◽  
Barbara Scherrer ◽  
Ludwig J. Gauckler
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Solid Solutions ◽  
Growth Kinetics ◽  
Scanning Calorimetry ◽  
Heating Chamber ◽  
Nanocrystalline Ceria ◽  
Average Grain Size ◽  
Grain Growth Kinetics ◽  
Kinetics Of

Nanocrystalline ceria-based thin films are of potential interest for use as gas-sensing layers and electrolytes in micro-Solid Oxide Fuel Cells (micro-SOFC) used for energy supply of next generation portables. In these devices the thin films have to be operated at intermediate to high temperatures (500 - 1000 °C) to be sufficiently high electrical conductive. However, only little is known on the nucleation and grain growth kinetics of pure ceria and its solid solutions when present as nanocrystalline thin film microstructures (average grain size < 100 nm). In this study amorphous, dense and crack-free CeO2 and Ce0.8Gd0.2O1.9-x thin films have been deposited by spray pyrolysis on sapphire. These films were crystallized to biphasic amorphous-nanocrystalline and fully nanocrystalline microstructures upon annealing with respect to time, temperature, heating rate and doping. Nucleation and grain growth kinetics were studied by differential scanning calorimetry, Xray diffraction analysis with in-situ heating chamber and scanning electron microscopy.

scholarly journals Grain Growth Kinetics of 0.65Ca0.61La0.26TiO3-0.35Sm(Mg0.5Ti0.5)O3 Dielectric Ceramic

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3905
Author(s):  
Jin Liu ◽  
Bingliang Liang ◽  
Jianjun Zhang ◽  
Wen He ◽  
Sheng Ouyang ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Prediction Accuracy ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Dielectric Ceramic ◽  
Nonlinear Regression Method ◽  
Grain Growth Kinetics ◽  
Grain Growth Behavior ◽  
Kinetics Of

The 0.65Ca0.61La0.26TiO3-0.35Sm(Mg0.5Ti0.5)O3[0.65CLT-0.35SMT] ceramic was prepared by the solid-state reaction method. The effects of sintering process on its microstructure and grain growth behavior were investigated. The Hillert model and a simplified Sellars model were established by linear regression, and the Sellars-Anelli model with a time index was established by using a nonlinear regression method. The results show that the grain size gradually increases with the increase of sintering temperature and holding time. Meanwhile, the sintering temperature has a more significant effect on the grain growth. The grain sizes of 0.65CLT-0.35SMT ceramic were predicted by the three models and compared with the experimentally measured grain size. The results indicate that for the 0.65CLT-0.35SMT ceramic, the Hillert model has the lowest prediction accuracy and the Sellars-Anelli model, the highest prediction accuracy. In this work, the Sellars-Anelli model can effectively predict the grain growth process of 0.65CLT-0.35SMT ceramic.

The kinetics of indium/amorphous-selenium multilayer thin film reactions

1999 ◽  
Vol 14 (3) ◽  
pp. 771-779 ◽  
Author(s):  
K. Lu ◽  
M. L. Sui ◽  
J. H. Perepezko ◽  
B. Lanning
Keyword(s):  
Interface Reaction ◽  
Amorphous Selenium ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Dimensional Growth ◽  
Kinetics Of ◽  
Modulation Wavelength

The reaction kinetics in vapor-deposited indium/amorphous-selenium (a-Se) multilayer thin films were studied using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). A number of reactions were observed upon heating with characteristic temperatures which were found to be independent of the multilayer modulation wavelength. The initial interface reaction between In and a-Se is the formation of an In2Se phase. Kinetic analyses of the In2Se formation process combined with TEM observations indicated that interface reaction is characterized by the two-dimensional growth of pre-existing In2Se regions formed during deposition to impingement in the plane of the original In/a-Se interface. The change of the density of In2Se grains with temperature was analyzed in terms of the derived kinetic parameters, which is consistent with TEM observations and the heat release measurements.

scholarly journals Monolithic nanocrystalline Au fabricated by the compaction of nanoscale foam

2005 ◽  
Vol 20 (3) ◽  
pp. 554-557 ◽  
Author(s):  
A.M. Hodge ◽  
J. Biener ◽  
L.L. Hsiung ◽  
Y.M. Wang ◽  
A.V. Hamza ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
X Ray Diffraction ◽  
Depth Sensing ◽  
Compaction Process ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Hardness Values

We describe a two-step dealloying/compaction process to produce nanocrystalline Au. First, nanocrystalline/nanoporous Au foam was synthesized by electrochemically driven dealloying. The resulting Au foams exhibited porosities of ∼60% with pore sizes of 40 and 100 nm and a typical grain size of <50 nm. Second, the nanoporous foams were fully compacted to produce nanocrystalline monolithic Au. The compacted Au was characterized by transmission electron microscopy and x-ray diffraction and tested by depth-sensing nanoindentation. The compacted nanocrystalline Au exhibited an average grain size of <50 nm and hardness values ranging from 1.4 to 2.0 GPa, which were up to 4.5 times higher than the hardness values obtained from polycrystalline Au.

scholarly journals Strain dependent grain growth during cold rolling deformation of gradient nanograined nickel

2020 ◽  
Vol 213 ◽  
pp. 02013
Author(s):  
Haitao Ni ◽  
Jiang Zhu ◽  
Heshan Yang ◽  
Yong Pu ◽  
Lixia Wang
Keyword(s):  
Grain Growth ◽  
Volume Fraction ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Small Grains ◽  
Grain Growth Behavior ◽  
Rolling Deformation ◽  
Rolling Strain

The effect of the rolling strain on grain growth behavior of two gradient nanograined nickel samples (average grain size ranging from 20~90nm) with symmetrical structure was investigated by scanning electron microscope/transmission electron microscopy observation, X-ray line profile analysis and microhardness measurement. In both gradient microstructures, under the same volume fraction, the layer with small grains and the layer with large grains was systematically compared. Quantitative analysis indicated that at a given nominal rolling strain small grains seem to grow more slowly than large grains, which can be attributed to the fact that the “hard” small grains sustain less deformation when the gradient are deformed to a certain strain.

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