A Study of Grain Growth in Ion Irradiated Co-Cr Alloy Films

1987 ◽  
Vol 93 ◽  
Author(s):  
J. Li ◽  
B. X. Liu ◽  
H. D. Li
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Grain Growth ◽  
Ion Irradiation ◽  
Alloy Films ◽  
Transmission Electron ◽  
Wide Range ◽  
Before And After ◽  
Bcc Structure ◽  
20 Nm

ABSTRACTExperiments concerning the behavior of grain size in Co80Cr20 alloy thin films upon ion irradiation were conducted. The alloy films of 80 nm thick were prepared by magnetron sputtering on cleaved NaCl crystal substrates, and then irradiated by 300 keV argon or xenon ions to a wide range of doses. The irradiated samples, before and after annealing, were examined by transmission electron microscope (TEM). It was found that the initial grain size with the dimension of 20 nm remained unchanged when the dose was less than 1×1016Ar/cm2, but rapidly reduced to the scale of 5 nm at a dose of 5×1016Ar/cm2. It is thought that this is due to a polymorphic transformation of an HCP to a BCC structure in the alloy films. After 30 min. anneals at 200° C, it was observed that the grain growth rate was a function of ion dose, and that there exists a critical fluence yielding a maximum grain growth rate. The possible mechanisms for the observations in this study are discussed.

Stability of Ruthenium-Silica Bilayer Structures

1994 ◽  
Vol 343 ◽  
Author(s):  
Zara Weng-Sieh ◽  
Tai. D. Nguyen ◽  
Ronald Gronsky
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Silicon Dioxide ◽  
Grain Growth ◽  
Original Film ◽  
Grain Sizes ◽  
Transmission Electron ◽  
20 Nm ◽  
Spherical Grains ◽  
Deposited Films

ABSTRACTThe microstructural evolution of ruthenium-silicon dioxide bilayer structures upon annealing is studied using transmission electron microscopy. SiO2/Ru/SiO2 structures, with thicknesses of 2/1/2 nm, 4/2/4 nm, 8/4/8 nm, and 20/10/20 nm, are formed by magnetron sputtering and annealed at 300 or 600°C. As-deposited films have grain sizes on the order of the Ru film thickness. After annealing at 600°C, significant grain growth is observed for all thicknesses, such that the final grain sizes are approximately 3 to 20x greater than the original film thickness. The largest increase in the average Ru grain size is observed for the 2 nm thick ruthenium film possibly due to the coalescence of Ru grains. The coalescence of the Ru particles in the 1 and 2 nm thick films results in the formation of lamellar Ru grains, which disrupts the contiguity of the Ru film. In all other cases, the increase in grain size is attributed to normal grain growth, but the formation of anomalous spherical grains is also observed.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

Behaviour of Nanocrystalline Silicon Carbide Under Low Energy Heavy Ion Irradiation

2009 ◽  
Vol 1215 ◽  
Author(s):  
Dominique Gosset ◽  
Laurence Luneville ◽  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Auregane Audren ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Grain Size ◽  
Ion Irradiation ◽  
Healing Process ◽  
Grazing Incidence ◽  
Nanocrystalline Silicon ◽  
Heavy Ion ◽  
Before And After ◽  
Gen Iv ◽  
Nanocrystalline Silicon Carbide

AbstractSilicon carbide is one of the most studied materials for core components of the next generation of nuclear plants (Gen IV). In order to overcome its brittle properties, materials with nanometric grain size are considered. In spite of the growing interest for nano-structured materials, only few experiments deal with their behaviour under irradiation. To assess and predict their evolution under working conditions, it is important to characterize their microstructure and structure. To this purpose, we have studied microcrystalline and nanocrystalline samples before and after irradiation at room temperature with 4 MeV Au ions. In fact, it is well established that such irradiation conditions lead to amorphisation of the material, which can be restored after annealing at high temperature. We have performed isochronal annealings of both materials to point out the characteristics of the healing process and eventual differences related to the initial microstructure of the samples. To this purpose Grazing Incidence X-Ray Diffraction has been performed to determine the microstructure and structure parameters. We observe the amorphisation of both samples at similar doses but different annealing kinetics are observed. The amorphous nanocrystalline sample recovers its initial crystalline state at higher temperature than the microcrystalline one. This effect is clearly related to the initial microstructures of the materials. Therefore, the grain size appears as a key parameter for the structural stability and mechanical properties of this ceramic material under irradiation.

scholarly journals Impurity influence on normal grain growth in the GISP2 ice core, Greenland

1996 ◽  
Vol 42 (141) ◽  
pp. 255-260 ◽  
Author(s):  
R. B Alley ◽  
G. A. Woods
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Isotopic Composition ◽  
Grain Growth ◽  
Forest Fire ◽  
Growth Rates ◽  
Slow Growth ◽  
Ice Core ◽  
Isotopic Data ◽  
Thin Sections

AbstractIntercept analysis of approximately bi-yearly vertical thin sections from the upper part of the GISP2 ice Core, central Greenland, shows that grain-size ranges increase with increasing age. This demonstrates that something in the ice affects grain-growth rates, and that grain-size cannot be used directly in paleothermometry as has been proposed. Correlation of grain-growth rates to chemical and isotopic data indicates slower growth in ice with higher impurity concentrations, and especially slow growth in “forest-fire” layers containing abundant ammonium; however, the impurity/grain-growth relations are quite noisy. Little correlation is found between growth rate and isotopic composition of ice.

Ion Induced Grain Growth in Pd

1991 ◽  
Vol 235 ◽  
Author(s):  
D. A. Lilienfeld ◽  
P. Bøorgesen ◽  
P. Meyer
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Growth ◽  
Low Temperatures ◽  
Nanocrystalline Materials ◽  
Ion Irradiation ◽  
Size Distributions ◽  
Careful Choice ◽  
Average Grain Size

ABSTRACTIon irradiation induced grain growth size distributions in Pd are examined at low temperatures. Two features are observed: 1) A majority of the grains saturate in size. 2) Some grains achieve sizes much larger than the average grain size and continue to grow with ion dose. However, by careful choice of ion mass and ion dose, it is possible to produce a sample possessing a monomodal grain size. This process will have applications in producing thin films of nanocrystalline materials.

Grain Growth Processes during Transient Annealing of As-Implanted, Polycrystalline-Silicon Films

1984 ◽  
Vol 35 ◽  
Author(s):  
S.J. Krause ◽  
S.R. Wilson ◽  
W.M. Paulson ◽  
R.B. Gregory
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Grain Growth ◽  
Polycrystalline Silicon ◽  
Average Diameter ◽  
Silicon Films ◽  
Growth Processes ◽  
Cross Sectional ◽  
Polycrystalline Silicon Films ◽  
Equiaxed Grains

ABSTRACTPolycrystalline silicon films of 300 nm thickness were deposited on oxidized wafer surfaces, implanted with As, and annealed on a Varian IA 200 rapid thermal annealer. Transmission electron microscopy was used to study through-thickness and cross sectional views of grain size and morphology of as-deposited and of transient annealed films. A bimoda] distribution of grain sizes was present in as-deposited polycrystalline silicon films. The first population was due to columnar growth of some grains to a final average diameter of 20 rm. The second population of small equiaxed grains of 5 nm average diameter were formed early in the deposition process. During transient annealing grains in the first population grew rapidly up to 280-nm equiaxed grains. After this the growth rate decreased due to the grain size reaching the thickness of the film. Grains in the second population grew rapidly up to a size of 150 nm, after which the growth rate was lowered due to grains impinging upon one another. The grain growth processes for both populations have been described with a modified model for interfacially driven grain growth. This model accounts for diffusion and grain growth which occur with rapidly rising and falling temperatures during short annealing times characteristic of transient annealing processes.

“In-Situ Network” Composite Fibers of Pbzt/Nylon

1988 ◽  
Vol 134 ◽  
Author(s):  
C. Robin Hwang ◽  
Michael F. Malone ◽  
Richard J. Farris ◽  
David C. Martin ◽  
Edwin L. Thomas
Keyword(s):  
Nitrogen Adsorption ◽  
Composite Fibers ◽  
Electron Microscopies ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Before And After ◽  
The Matrix ◽  
Novel Method ◽  
20 Nm

ABSTRACTA novel method of preparing PBZT/nylon composite fibers by infiltrating nylon into pure PBZT fiber is described. The pure PBZT fiber formed a microfibrillar network structure during coagulation, which is effective in reinforcing the matrix in the “in-situ network” composite fibers (designated IC). These new composite fibers exhibit nearly indistinguishable mechanical properties as those of “molecular” composite fibers (MC) prepared from isotropic solutions before and after tension heat-treatment (E = 44 GPa, σ = 430 MPa, ε = 1.2 %, σc = 250 MPa, G = 1.75 GPa) for PBZT/nylon weight ratios equal to unity.The fine structure of pure PBZT and its composite fibers spun from isotropic solutions was characterized using techniques based on nitrogen adsorption, small-angle X-ray scattering, scanning and transmission electron microscopies. The structure of both type of composites was found to be a microfibrillar network of PBZT in a matrix of amorphous nylon. The average diameters of the PBZT microfibrils were in the range of 10 to 20 nm for the IC and 4 nm for the MC.

scholarly journals Effect of He-appm/DPA ratio on the damage microstructure of tungsten

MRS Advances ◽  
2016 ◽  
Vol 1 (42) ◽  
pp. 2893-2899 ◽  
Author(s):  
R.W. Harrison ◽  
H. Amari ◽  
G. Greaves ◽  
J.A. Hinks ◽  
S.E. Donnelly
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
Dislocation Loops ◽  
Vacancy Clusters ◽  
Transmission Electron ◽  
Damage Structure ◽  
Ordered Array ◽  
20 Nm

AbstractIn-situ ion irradiation and transmission electron microscopy has been used to examine the effects of the He appm to DPA ratio, temperature and dose on the damage structure of tungsten (W). Irradiations were performed with 15 or 60 keV He+ ions, achieving He-appm/displacements per atom (DPA) ratios of ∼40,000 and ∼2000, respectively, at temperatures between 500 and 1000°C to a dose of ∼3 DPA. A high number of small dislocation loops with sizes around 5–20 nm and a He bubble lattice were observed for both He-appm/DPA ratios at 500°C with a bubble size ∼1.5 nm. Using the g.b=0 criterion the loops were characterised as b = ±1/2<111> type. At 750°C bubbles do not form an ordered array and are larger in size compared to the irradiations at 500°C, with a diameter of ∼3 nm. Fewer dislocation loops were observed at this temperature and were also characterised to be b = ±1/2<111> type. At 1000°C, no dislocation loops were observed and bubbles grew as a function of fluence attributed to vacancy mobility being higher and vacancy clusters becoming mobile.

scholarly journals Enhancement of GAD Storage Stability with Immobilization on PDA-Coated Superparamagnetic Magnetite Nanoparticles

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 969 ◽  
Author(s):  
Farheen Zafar ◽  
Hong-peng Wang ◽  
Chang-jiang Lv ◽  
Muhammad-Haseeb Ullah ◽  
Chun-yan Liu ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Storage Stability ◽  
Specific Activity ◽  
Precipitation Method ◽  
Acid Decarboxylase ◽  
Relative Specific Activity ◽  
Transmission Electron ◽  
Before And After ◽  
Co Precipitation ◽  
20 Nm

To improve the storage stability of glutamic acid decarboxylase (GAD), superparamagnetic magnetite (Fe3O4) nanoparticles were synthesized by co-precipitation method and coated with polydopamine (PDA) for GAD immobilization. Dynamic light scattering and transmission electron microscopy were used to determine size of the nanoparticles, which were approximately 10 nm, increasing to 15 nm after PDA-coating and to 20 nm upon GAD binding. Vibrational scanning measurements significantly represented the superparamagnetic behavior of the Fe3O4, and X-ray diffraction analysis confirmed that the crystalline structure before and after coating with PDA and the further immobilization of GAD remained the same. Thermogravimetric analysis and Fourier-transform infrared spectroscopy proved that the PDA-coating on Fe3O4 and further immobilization of GAD were successful. After immobilization, the enzyme can be used with a relative specific activity of 40.7% after five successive uses. The immobilized enzyme retained relative specific activity of about 50.5% after 15 days of storage at 4 °C, while free enzyme showed no relative specific activity after two days of storage. The GAD immobilization on PDA-coated magnetite nanoparticles was reported for the improvement of enzyme storage stability for the first time.

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