scholarly journals Forming pressure effect on microstructure and mechanical properties of nanocrystalline aluminum synthesized by inert gas condensation

2019 ◽  
Vol 79 ◽  
pp. 02002
Author(s):  
Shangshu Wu ◽  
Zhou Yu ◽  
Junjie Wang ◽  
Hanxin Zhang ◽  
Chaoqun Pei ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Vacuum ◽  
Inert Gas ◽  
Helium Atmosphere ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
In Situ Forming ◽  
Nanocrystalline Aluminum ◽  
Al Powder

The preparation of nanocrystalline aluminum (NC Al) was conducted in two steps. After the NC Al powder was synthesized by an Inert gas condensation (IGC) method in a helium atmosphere of 500 Pa, the NC Al powder was in-situ compacted into a pellet with a 10 mm diameter and 250 μm-300 μm thickness in a high vacuum (10-6 Pa-10-7 Pa) at room temperature. The NC Al samples were not exposed to air during the entire process. After the pressure reached 6 GPa, the relative density could reach 99.83%. The results showed that the grain size decreased with the increased of in-situ forming pressure. The NC Al samples present obvious ductile fracture, and the tensile properties were greatly changed with the increase of forming pressure.

EFFECTIVE MAGNETIC ANISOTROPY AND COERCIVITY IN Fe NANOPARTICLES PREPARED BY INERT GAS CONDENSATION

2006 ◽  
Vol 20 (01) ◽  
pp. 37-47
Author(s):  
LUBNA RAFIQ SHAH ◽  
BAKHTYAR ALI ◽  
S. K. HASANAIN ◽  
A. MUMTAZ ◽  
C. BAKER ◽  
...  
Keyword(s):  
Room Temperature ◽  
Size Range ◽  
Magnetic Measurements ◽  
Uniaxial Anisotropy ◽  
Inert Gas ◽  
Condensation Process ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Fe Nanoparticles ◽  
Characterization Studies

We present magnetic measurements on iron ( Fe ) nanoparticles in the size range 10–30 nm produced by the Inert Gas Condensation process (IGC). Structural characterization studies show the presence of a core/shell structure, where the core is bcc Fe while the surface layer is Fe -oxide. Analysis of the magnetic measurements shows that the nanoparticles display very large uniaxial anisotropy, K eff ≈3 - 4 × 106 erg/cc. The observed room temperature coercivities lie in the range ≈600 – 973 Oe , much larger than those expected from the Stoner–Wohlfarth model using the bulk iron anisotropy. It can be inferred from the coercivity variation with the particle size that there is a general trend of the coercivity increasing with size, culminating finally in a decrease for high sizes (30 nm) possibly due to the onset of non-coherent magnetization reversal processes.

TEM Observation of Nanocrystalline Copper During Deformation

2000 ◽  
Vol 634 ◽  
Author(s):  
Carl J. Youngdahl ◽  
Richard C. Hugo ◽  
Harriet Kung ◽  
Julia R. Weertman
Keyword(s):  
Grain Size ◽  
Stress Concentration ◽  
Real Time ◽  
Dislocation Motion ◽  
Inert Gas ◽  
Nanocrystalline Copper ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Small Cracks

ABSTRACTNanocrystalline samples of copper were prepared using inert gas condensation and an optimized sequence of powder outgassing and compaction. TEM specimens were cut, electropolished, and mounted in a straining stage. In situ TEM observations including real-time video were captured during straining in the microscope. Areas of presumed increased stress concentration were identified near small cracks around the perimeter of the electropolished hole. Such locations were observed in the TEM while the specimen was pulled in tension. Several microstructural changes were captured during deformation including numerous sudden shifts in contrast of grains and parts of grains, occasional dislocation motion, opening and propagation of the crack. Relationships between grain size and deformation are described.

scholarly journals Synthesis of Fe Nanoparticles Functionalized with Oleic Acid Synthesized by Inert Gas Condensation

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
L. G. Silva ◽  
F. Solis-Pomar ◽  
C. D. Gutiérrez-Lazos ◽  
Manuel F. Meléndrez ◽  
E. Martinez ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Quadrupole Mass Filter ◽  
Inert Gas ◽  
Quadrupole Mass ◽  
Mass Filter ◽  
Zone Length ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Fe Nanoparticles

In this work, we study the synthesis of monodispersed Fe nanoparticles (Fe-NPs)in situfunctionalized with oleic acid. The nanoparticles were self-assembled by inert gas condensation (IGC) technique by using magnetron-sputtering process. Structural characterization of Fe-NPs was performed by transmission electron microscopy (TEM). Particle size control was carried out through the following parameters: (i) condensation zone length, (ii) magnetron power, and (iii) gas flow (Ar and He). Typically the nanoparticles generated by IGC showed diameters which ranged from ~0.7 to 20 nm. Mass spectroscopy of Fe-NPs in the deposition system allowed the study ofin situnanoparticle formation, through a quadrupole mass filter (QMF) that one can use together with a mass filter. When the deposition system works without quadrupole mass filter, the particle diameter distribution is around +/−20%. When the quadrupole is in line, then the distribution can be reduced to around +/−2%.

scholarly journals Synthesis, Characterization and Mechanical Properties of Nanocrystalline NiAl

1996 ◽  
Vol 457 ◽  
Author(s):  
M. S. Choudry ◽  
J. A. Eastman ◽  
R. J. DiMelfi ◽  
M. Dollar
Keyword(s):  
Room Temperature ◽  
Dark Field ◽  
Inert Gas ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Grain Sizes ◽  
Room Temperature Ductility ◽  
Cast Alloys ◽  
Bend Tests

ABSTRACTNanocrystalline NiAl has been produced from pre-cast alloys using an electron beam inert gas condensation system. In-situ compaction was carried out at 100 to 300°C under vacuum conditions. Energy dispersive spectroscopy was used to determine chemical composition and homogeneity. Average grain sizes in the range of 4 to 10 nm were found from TEM dark field analyses. A compression-cage fixture was designed to perform disk bend tests. These tests revealed substantial room temperature ductility in nanocrystalline NiAl, while coarse grained NiAl showed no measurable room temperature ductility.

Recent study of nanomaterials prepared by inert gas condensation using ultra high vacuum chamber

Pramana ◽  
2005 ◽  
Vol 65 (5) ◽  
pp. 881-891 ◽  
Author(s):  
S. Ramasamy ◽  
D. J. Smith ◽  
P. Thangadurai ◽  
K. Ravichandran ◽  
T. Prakash ◽  
...  
Keyword(s):  
Vacuum Chamber ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Inert Gas ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
High Vacuum Chamber ◽  
Ultra High Vacuum Chamber

THE COMPLEXITY OF THE GROWTH AND OPTICAL PROPERTIES OF GERMANIUM NANOCLUSTERS

1996 ◽  
Vol 03 (01) ◽  
pp. 91-95
Author(s):  
MIN HAN ◽  
YANCHUN GONG ◽  
JIANXIN MA ◽  
FENGQI LIU ◽  
GUANGHOU WANG
Keyword(s):  
Quantum Confinement ◽  
Room Temperature ◽  
Quantum Confinement Effect ◽  
Preparation Condition ◽  
Inert Gas ◽  
Fractal Structures ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Near Ir ◽  
Aggregation Processes

Germanium nanoclusters are prepared by means of the inert-gas condensation method. The growth, coalescence, and aggregation processes are investigated by means of TEM. It is found that the clusters can be either nanocrystals or amorphous-like. Furthermore, during the deposition, they can either randomly land on surface, keep isolated and finally form a cluster-assembled uniform film or aggregate with fractal structures and then form porous film, depending on their preparation condition. Spectropho-tometric measurements are recorded for these samples at room temperature in the ultraviolet, visible, and near-IR region, and show obvious blueshift of the band gap as large as 1.0–2.0 eV in comparison with those for the bulk specimens, which may be related to the quantum-confinement effect.

Indium Antimonide Nanoparticles Synthesized using Inert Gas Condensation Technique.

2015 ◽  
Vol 1784 ◽  
Author(s):  
Sneha G. Pandya ◽  
Martin E. Kordesch
Keyword(s):  
Indium Antimonide ◽  
High Vacuum ◽  
Bimodal Distribution ◽  
Growth Direction ◽  
Inert Gas ◽  
Cubic Symmetry ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Average Grain Size ◽  
Scherrer Formula

ABSTRACTNanoparticles (NPs) of Indium Antimonide (InSb) were synthesized using a vapor phase synthesis technique known as Inert Gas Condensation. NPs were directly deposited, at room temperature and under high vacuum, on glass cover slides, TEM grid, 1 inch-square (111) p-type Silicon wafer and Sodium Chloride substrates. XRD study revealed the crystalline behavior of these NPs exhibiting a cubic symmetry with preferred growth direction of (111). The average grain size of the NPs obtained using XRD results and the Debye-Scherrer formula was 25.62 nm. TEM studies showed a bimodal distribution of NPs with average NPs size of 13.70 and 33.20 nm. These values are consistent with the value obtained using XRD. 1:1 composition ratio of In:Sb was confirmed by the Energy Dispersive X-Ray Spectroscopy studies. The band gap of the NPs obtained using Fourier Transform Infrared (FTIR) spectroscopy was 0.413 eV at 300 K, which indicates quantum confinement in the band structure of these NPs.

Solid State Reactions In Binary Mixtures Of Nanometer-Sized Particles

1993 ◽  
Vol 321 ◽  
Author(s):  
W. Dickenscheid ◽  
R. Birringer
Keyword(s):  
Thermal Analysis ◽  
Solid State ◽  
Inert Gas ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
Annealing Behavior ◽  
X Ray ◽  
Gas Condensation ◽  
Inert Gas Condensation

ABSTRACTSolid state reactions in mixtures of nanometer-sized Cu and Zr as well as Ni and Zr crystallites -produced by inert-gas condensation followed by in situ compaction - have been investigated by x-ray diffraction and thermal analysis. The annealing behavior is compared to that of corresponding multilayer samples. The results are discussed with emphasis placed on the different parameters controlling solid state reactions.

scholarly journals Phase Control in Nanophase Materials Formed from Ultrafine Ti Or Pd Powders

1988 ◽  
Vol 132 ◽  
Author(s):  
J. A. Eastman
Keyword(s):  
Amorphous Phase ◽  
Crystalline Phase ◽  
Ultrafine Particles ◽  
Room Temperature ◽  
Inert Gas ◽  
Ultrafine Powders ◽  
Gas Condensation ◽  
Inert Gas Condensation ◽  
Nanophase Materials ◽  
Fcc Phase

ABSTRACTThe effect of He gas pressure during evaporation and post-evaporation O2 exposure on phase formation in nanophase materials has been examined. Ultrafine powders of Ti and Pd were prepared by the inert gas-condensation technique and bulk nanophase samples were formed by consolidation of these powders with or without prior exposure to O2. Evaporation of Ti in He pressures greater than 500 Pa followed by exposure to O2 results in the formation of ultrafine powders of crystalline rutile (TiO2) which are compacted to form nanocrystalline TiO2. Surprisingly, reducing the He pressure used during evaporation to less than approximately 500 Pa results in the formation of ultrafine powders of an amorphous phase. Room temperature consolidation of this powder under vacuum, however, results in nanocrystalline Ti being formed if the powder is not exposed to O2 prior to consolidation, and a mixture of rutile and an unidentified crystalline phase if the powder has been previously exposed to O2. Further reduction of the He pressure during evaporation of Ti to less than approximately 10 Pa results in the formation of crystalline Ti having a film-like morphology rather than than the desired ultrafine particles. Experiments on Pd evaporated in 10 to 6000 Pa of He have yielded ultrafine powders and consolidated samples of only the crystalline fcc phase, regardless of the He pressure

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