Powder processing of ductile materials for high pressure studies: application to intermetallic alloys

1997 ◽  
Vol 499 ◽  
Author(s):  
J. W. Otto ◽  
G. Frommeyer ◽  
J. K. Vassiliou
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Mechanical Alloying ◽  
Powder Processing ◽  
Gas Atomization ◽  
Intermetallic Alloys ◽  
Pressure Work ◽  
Ductile Materials ◽  
High Pressure Studies ◽  
Good Agreement

ABSTRACTDuctile materials are difficult to powderize for use in high pressure work. The potential of different techniques (gas-atomization, mechanical alloying, ball milling and subsequent annealing) for preparing suitable powders of some aluminides is investigated. Compression of Ti46Al54 and NiAl prepared by these methods yields equation of state parameters in good agreement with determinations by other methods.

scholarly journals Local-Basis-Function Equation of State for Ice VII–X to 450 GPa at 300 K

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 92 ◽  
Author(s):  
J. Michael Brown ◽  
Baptiste Journaux
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Current Method ◽  
Helmholtz Energy ◽  
Proton Mobility ◽  
Pressure Derivative ◽  
Local Basis ◽  
High Pressure Studies

Helmholtz energy of ice VII–X is determined in a pressure regime extending to 450 GPa at 300 K using local-basis-functions in the form of b-splines. The new representation for the equation of state is embedded in a physics-based inverse theory framework of parameter estimation. Selected pressures as a function of volume from 14 prior experimental studies and two theoretical studies constrain the behavior of Helmholtz energy. Separately measured bulk moduli, not used to construct the representation, are accurately replicated below about 20 GPa and above 60 GPa. In the intermediate range of pressure, the experimentally determined moduli are larger and have greater scatter than values predicted using the Helmholtz representation. Although systematic error in the determination of elastic moduli is possible and likely, the alternative hypothesis is a slow relaxation time associated with changes in proton mobility or the ice VII to X transition. A correlation is observed between anomalies in the pressure derivative of the predicted bulk modulus and previously suggested higher-order phase transitions. Improved determinations of elastic properties at high pressure would allow refinement of the current equation of state. More generally, the current method of data assimilation is broadly applicable to other materials in high-pressure studies and for investigations of planetary interiors.

Benefits of Rapid Solidification Processing of Modified LaNi5 Alloys by High Pressure Gas Atomization for Battery Applications

1997 ◽  
Vol 496 ◽  
Author(s):  
I. E. Anderson ◽  
V. K. Pecharsky ◽  
J. Ting ◽  
C. Witham ◽  
R. C. Bowman
Keyword(s):  
High Pressure ◽  
Rapid Solidification ◽  
Powder Processing ◽  
Microstructural Analysis ◽  
Hydrogen Gas ◽  
Gas Atomization ◽  
Industrial Practice ◽  
Phase Cycling ◽  
Gas Cycling ◽  
Annealing Experiments

ABSTRACTA high pressure gas atomization approach to rapid solidification has been employed to investigate simplified processing of Sn modified LaNi5 powders that can be used for advanced Ni/metal hydride (Ni/MH) batteries. The current industrial practice involves casting large ingots followed by annealing and grinding and utilizes a complex and costly alloy design. This investigation is an attempt to produce powders for battery cathode fabrication that can be used in an as-atomized condition without annealing or grinding. Both Ar and He atomization gas were tried to investigate rapid solidification effects. Sn alloy additions were tested to promote subambient pressure absorption/desorption of hydrogen at ambient temperature. The resulting fine, spherical powders were subject to microstructural analysis, hydrogen gas cycling, and annealing experiments to evaluate suitability for Ni/MH battery applications. The results demonstrate that a brief anneal is required to homogenize the as-solidified microstructure of both Ar and He atomized powders and to achieve a suitable hydrogen absorption behavior. The Sn addition also appears to suppress cracking during hydrogen gas phase cycling in particles smaller than about 25μm. These results suggest that direct powder processing of a LaNi5−xSnx alloy has potential application in rechargeable Ni/MH batteries.

scholarly journals Local-Basis-Function Equation of State for Ice VII-X to 450 GPa at 300 K

2019 ◽  
Author(s):  
J. Michael Brown ◽  
Baptiste Journaux
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Current Method ◽  
Helmholtz Energy ◽  
Proton Mobility ◽  
Pressure Derivative ◽  
Local Basis ◽  
High Pressure Studies

Helmholtz energy of ice VII-X is determined in a pressure regime extending to 450 GPa at 300 K using local basis functions in the form of b splines. The new representation for the equation of state is embedded in a physics-based inverse theory framework of parameter estimation. Selected pressures as a function of volume from 14 prior experimental studies and two theoretical studies constrain the behavior of Helmholtz energy. Separately measured bulk moduli, not used to construct the representation, are accurately replicated below about 20 GPa and above 60 GPa. In the intermediate range of pressure, the experimentally determined moduli are larger and have greater scatter than values predicted using the Helmholtz representation. Although systematic experimental error in the experimental elastic moduli is possible and likely, the alternative hypothesis is a slow relaxation time associated with changes in proton mobility or the ice VII to X transition. A correlation is observed between anomalies in the pressure derivative of the predicted bulk modulus and previously suggested higher-order phase transitions. Improved determinations of elastic properties at high pressure would allow refinement of the current equation of state. More generally, the current method of data assimilation is broadly applicable to other materials in high-pressure studies.

Equation of state of polycrystalline Ni50Al50

1997 ◽  
Vol 12 (11) ◽  
pp. 3106-3108 ◽  
Author(s):  
J. W. Otto ◽  
J. K. Vassiliou ◽  
G. Frommeyer
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
Inert Gas ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
High Pressure Studies ◽  
Diamond Anvil

Polycrystalline Ni50Al50 suitable for high pressure studies was prepared by grinding and subsequent annealing of an inert-gas atomized alloy. The equation of state was determined by energy-dispersive x-ray diffraction in a diamond anvil cell to 25 GPa. The bulk modulus Bo and the pressure derivative of the bulk modulus B′o were found to be Bo = 156 ± 3 GPa and B′o = 4.0 ± 0.5.

High Pressure Studies of Quantum Well Emission and Deep Emission in GaInP(ordered)-GaAs Heterostructures

1997 ◽  
Vol 499 ◽  
Author(s):  
S. H. Kwok ◽  
P. Y. Yu ◽  
K. Uchida ◽  
T. Arai
Keyword(s):  
High Pressure ◽  
Quantum Well ◽  
Emission Band ◽  
Excitation Power ◽  
High Excitation ◽  
High Pressure Studies ◽  
Band Alignments ◽  
High Pressure Study

ABSTRACTWe report on a high pressure study of emission from a series of GaInP(ordered)/GaAs heterostructures. A so-called “deep emission” band at 1.46 eV is observed in all our samples. At high excitation power, quantum well emission emerges in only one structure where thin GaP layers are inserted on both sides of the GaAs well. From the pressure dependent emission in this sample we have determined its band alignments. The role of the GaP layers in suppressing the deep emission is elucidated.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

scholarly journals Equation of state studies at SILP by laser-driven shock waves

1996 ◽  
Vol 14 (2) ◽  
pp. 157-169 ◽  
Author(s):  
Yuan Gu ◽  
Sizu Fu ◽  
Jiang Wu ◽  
Songyu Yu ◽  
Yuanlong Ni ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Equation Of State ◽  
Shock Waves ◽  
Target Surface ◽  
Shock Adiabats ◽  
Pressure Shock ◽  
Aluminum Target ◽  
Laser Illumination ◽  
The Stability

The experimental progress of laser equation of state (EOS) studies at Shanghai Institute of Laser Plasma (SILP) is discussed in this paper. With a unique focal system, the uniformity of the laser illumination on the target surface is improved and a laser-driven shock wave with good spatial planarity is obtained. With an inclined aluminum target plane, the stability of shock waves are studied, and the corresponding thickness range of the target of laser-driven shock waves propagating steadily are given. The shock adiabats of Cu, Fe, SiO2 are experimentally measured. The pressure in the material is heightened remarkably with the flyer increasing pressure, and the effect of the increasing pressure is observed. Also, the high-pressure shock wave is produced and recorded in the experimentation of indirect laser-driven shock waves with the hohlraum target.

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