Film evolution and growth mechanism of a Ni-based superalloy in the two models at the different temperatures

Vacuum ◽  
2021 ◽  
pp. 110538
Author(s):  
H.U. Ye-Bing ◽  
C.H.E.N.G. Cong-Qian ◽  
Tie-Shan Cao ◽  
Li Zhang ◽  
Jie Zhao
Keyword(s):  
Growth Mechanism ◽  
Different Temperatures

Controlled Hydrothermal Growth of CuO-Based Nanostructures from Copper Alginate

2011 ◽  
Vol 688 ◽  
pp. 19-22 ◽  
Author(s):  
Bing Bing Wang ◽  
Qing Shan Kong ◽  
Jian Ping Sun ◽  
Quan Feng Yu ◽  
Quan Ji ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Growth Mechanism ◽  
Hydrothermal System ◽  
Ph Value ◽  
Structure Evolution ◽  
Structure Directing Agent ◽  
Aggregation State ◽  
Air Atmosphere ◽  
Morphology And Structure ◽  
Different Temperatures

Schistose and aciculate CuO nanostructures have been synthesized by a novel ammonia assisted hydrothermal method of copper alginate. The conversion processes of copper alginate are investigated by thermogravimetrics (TG) analyses under N2and air atmosphere. The morphology, structure, and composition of the obtained CuO are investigated using SEM,TEM and XRD. It is found that different temperature and pH value resulted in the morphology and structure evolution of CuO. Ammonia was used as structure-directing agent in the hydrothermal system. The aggregation state of the nanostructures was controlled by the temperature. Dispersive schistose structures about 1μm in diameter were synthesized with 0.5mL ammonia at different temperatures. Dispersive microspheres of about 4 μm in diameter were also synthesized with 1 mL ammonia. Microspheres composed of nanoneedles and nanoplates were synthesized at 120°C and 160°C, respectively. Moreover, a possible growth mechanism governing the formation of such a nanomicrostructure was primarily discussed.

scholarly journals Grain Growth Mechanism of Lamellar-Structure High-Purity Nickel via Cold Rolling and Cryorolling during Annealing

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4025
Author(s):  
Zhide Li ◽  
Yuze Wu ◽  
Zhibao Xie ◽  
Charlie Kong ◽  
Hailiang Yu
Keyword(s):  
Grain Growth ◽  
Growth Mechanism ◽  
High Purity ◽  
Lamellar Structure ◽  
Room Temperature ◽  
Rolling Process ◽  
Deformation Energy ◽  
Different Temperatures ◽  
Continuous Recrystallization ◽  
Room Temperature Rolling

High-purity (99.999%) nickel with lamellar-structure grains (LG) was obtained by room-temperature rolling and cryorolling in this research, and then annealed at different temperatures (75 °C, 160 °C, and 245 °C). The microstructure was characterized by transmission electron microscopy. The grain growth mechanism during annealing of the LG materials obtained via different processes was studied. Results showed that the LG high-purity nickel obtained by room-temperature rolling had a static discontinuous recrystallization during annealing, whereas that obtained by cryorolling underwent static and continuous recrystallization during annealing, which was caused by the seriously inhibited dislocation recovery in the rolling process under cryogenic conditions, leading to more accumulated deformation energy storage in sheets.

scholarly journals Research on Irreversible Growth Mechanism of PBX due to Thermal Cycling

2021 ◽  
Vol 257 ◽  
pp. 01051
Author(s):  
Siyang Lei ◽  
Shuo Wang ◽  
Fangyun Lu ◽  
Rong Chen
Keyword(s):  
High Temperature ◽  
Creep Rate ◽  
Low Temperature ◽  
Thermal Cycling ◽  
Growth Mechanism ◽  
Viscoelastic Model ◽  
Temperature Cycling ◽  
Creep Properties ◽  
Different Temperatures ◽  
Polymer Bonded Explosives

Current experiments show that the TATB-based polymer bonded explosives (PBX) will experience irreversible growth when suffered temperature cycling load. Although some studies have already been done on this, the cause of irreversible growth is still confusing, and the mechanism is not clear. In order to study the irreversible growth of PBX under temperature cycling load, an thermal-viscoelastic model is established, Based on the Burgers model which considering the influence of different temperatures on the creep properties of PBX. The analysis shows that the irreversible growth of PBX produced by the different creep properties of high and low temperature during the thermal cycling. Comparing with low temperature, the creep rate of PBX is faster and the deformation is larger at high temperature, which lead to the irreversible growth of PBX.

scholarly journals Formation of Germanium Nitride Nanowires on the Surface of Crystalline Germanium

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
David Jishiashvili ◽  
Lasha Kiria ◽  
Zeinab Shiolashvili ◽  
Nino Makhatadze ◽  
Elguja Miminoshvili ◽  
...  
Keyword(s):  
Single Crystal ◽  
Growth Mechanism ◽  
Cross Sections ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Vapor Liquid Solid ◽  
Temperature Range ◽  
Nucleation Stage ◽  
Vapor Liquid Solid Mechanism ◽  
Different Temperatures

We report on the growth mechanisms of germanium nitride nanowires on the surface of crystalline Ge annealed in hydrazine vapor at different temperatures. In spite of the presence of water (and hence oxygen precursors) in hydrazine, the pure germanium nitride single crystal nanowires were produced in the temperature range of 480–580°C. At temperatures below 520°C, the GeOx clusters were formed first at the Ge surface, followed by the nucleation and growth of nanowires through the Vapor-Liquid-Solid mechanism. The Vapor-Solid growth mechanism was observed at temperatures exceeding 520°C, and Ge3N4 nanobelts were produced instead of nanowires with circular cross-sections. All nanostructures have the alpha germanium nitride structure; however, at the nucleation stage, the presence of beta Ge3N4 phase was also observed in the roots of nanowires.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Montmorillonite Dendrites

1974 ◽  
Vol 32 ◽  
pp. 454-455
Author(s):  
Necip Güven ◽  
Rodney W. Pease
Keyword(s):  
Crystal Growth ◽  
Growth Mechanism ◽  
Growth Front ◽  
Morphological Features ◽  
Dendritic Crystal ◽  
Crystal Growth Mechanism

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

Structural phenomena in the growth of carbon nanotubes

1993 ◽  
Vol 51 ◽  
pp. 750-751
Author(s):  
Jun Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Growth Mechanism ◽  
Carbonaceous Material ◽  
Cluster Growth ◽  
Structural Elements ◽  
Rich Variety ◽  
Different Shapes ◽  
Point To Point

HREM studies of the carbonaceous material deposited on the cathode of a Huffman-Krätschmer arc reactor have shown a rich variety of multiple-walled nano-clusters of different shapes and forms. The preparation of the samples, as well as the variety of cluster shapes, including triangular, rhombohedral and pentagonal projections, are described elsewhere.The close registry imposed on the nanotubes, focuses attention on the cluster growth mechanism. The strict parallelism in the graphitic separation of the tube walls is maintained through changes of form and size, often leading to 180° turns, and accommodating neighboring clusters and defects. Iijima et. al. have proposed a growth scheme in terms of pentagonal and heptagonal defects and their combinations in a hexagonal graphitic matrix, the first bending the surface inward, and the second outward. We report here HREM observations that support Iijima’s suggestions, and add some new features that refine the interpretation of the growth mechanism. The structural elements of our observations are briefly summarized in the following four micrographs, taken in a Hitachi H-8100 TEM operating at an accelerating voltage of 200 kV and with a point-to-point resolution of 0.20 nm.

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