Stabilization of spent sorbents from coal gasification. Technical report, December 1, 1992--February 28, 1993 (open access)

Stabilization of spent sorbents from coal gasification. Technical report, December 1, 1992--February 28, 1993

The objective of this investigation is to determine the kinetics of reactions involving partially sulfided dolomite and oxygen, which is needed for the design of the reactor system for the stabilization of sulfide-containing solid wastes from gasification of high sulfur coals. To achieve this objective, samples of partially sulfided dolomite are reacted with oxygen at a variety of operating conditions in a fluidized-bed reactor, where external diffusion limitations are avoided by using small quantities of the sorbent and maintaining a high flow rate of the reactant gas. The reacted sorbents are analyzed to determine the extent of conversion as a function of operating variables including sorbent particle size, reaction temperature and pressure, and oxygen concentration. Samples of the partially sulfided dolomite were reacted with oxygen in the fluidized-bed rector at different operating conditions. The test parameters included the effects of solid residence time, oxygen concentration, and reaction temperature. The reacted solids were analyzed to determine the extent of CaS conversion to CaSO{sub 4}. The results of the tests conducted so far in the project indicate that the extent of conversion increase with increasing oxygen concentration and the solid residence time. The rate of reaction appears to be very sensitive to …
Date: May 1, 1993
Creator: Abbasian, J.; Hill, A. H.; Wangerow, J. R. & Banerjee, D. D.
Object Type: Report
System: The UNT Digital Library
Health effects models for nuclear power plant accident consequence analysis. Modification of models resulting from addition of effects of exposure to alpha-emitting radionuclides: Revision 1, Part 2, Scientific bases for health effects models, Addendum 2 (open access)

Health effects models for nuclear power plant accident consequence analysis. Modification of models resulting from addition of effects of exposure to alpha-emitting radionuclides: Revision 1, Part 2, Scientific bases for health effects models, Addendum 2

The Nuclear Regulatory Commission (NRC) has sponsored several studies to identify and quantify, through the use of models, the potential health effects of accidental releases of radionuclides from nuclear power plants. The Reactor Safety Study provided the basis for most of the earlier estimates related to these health effects. Subsequent efforts by NRC-supported groups resulted in improved health effects models that were published in the report entitled {open_quotes}Health Effects Models for Nuclear Power Plant Consequence Analysis{close_quotes}, NUREG/CR-4214, 1985 and revised further in the 1989 report NUREG/CR-4214, Rev. 1, Part 2. The health effects models presented in the 1989 NUREG/CR-4214 report were developed for exposure to low-linear energy transfer (LET) (beta and gamma) radiation based on the best scientific information available at that time. Since the 1989 report was published, two addenda to that report have been prepared to (1) incorporate other scientific information related to low-LET health effects models and (2) extend the models to consider the possible health consequences of the addition of alpha-emitting radionuclides to the exposure source term. The first addendum report, entitled {open_quotes}Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting from Recent Reports on Health Effects of Ionizing Radiation, Low …
Date: May 1, 1993
Creator: Abrahamson, S.; Bender, M. A.; Boecker, B. B.; Scott, B. R. & Gilbert, E. S.
Object Type: Report
System: The UNT Digital Library
Flat beams in the SLC (open access)

Flat beams in the SLC

The Stanford Linear collider was designed to operate with round beams; horizontal and vertical emittance made equal in the damping rings. The main motivation was to facilitate the optical matching through beam lines with strong coupling elements like the solenoid spin rotator magnets and the SLC arcs. Tests in 1992 showed that ``flat`` beams with a vertical to horizontal emittance ratio of around 1/10 can be successfully delivered to the end of the linac. Techniques developed to measure and control the coupling of the SLC arcs allow these beams to be transported to the Interaction Point (IP). Before flat beams could be used for collisions with polarized electrons, a new method of rotating the electron spin orientation with vertical arc orbit bumps had to be developed. Early in the 1993 run, the SLC was switched to ``flat`` beam operation. Within a short time the peak luminosity of the previous running cycle was reached and then surpassed. The average daily luminosity is now a factor of about two higher than the best achieved last year. In the following we present an overview of the problems encountered and their solutions for different parts of the SLC.
Date: May 1, 1993
Creator: Adolphsen, C.; Barklow, T. & Burke, D.
Object Type: Article
System: The UNT Digital Library
A search for strong-field direct two electron ionization using coincidence spectroscopy (open access)

A search for strong-field direct two electron ionization using coincidence spectroscopy

We report on our program in detecting two-electron ionization using electron-electron and electron-ion coincidence measurements. The coincidence techniques have been applied to the multiphoton ionization (MPI) of xenon atoms with 0.527 {mu}m excitation. The results show that direct two electron ionization is not occurring which is in variance with an earlier report. We also present a polarization study on the MPI of helium at 0.62 {mu}m and discuss these results in context of existing models.
Date: May 1, 1993
Creator: Agostini, P.; Mevel, E.; Breger, P.; Walker, B.; Yang, B. & DiMauro, L. F.
Object Type: Article
System: The UNT Digital Library
A Computational Model for Coal Transport and Combustion. Quarterly Technical Progress Report, December 1, 1992--February 28, 1993 (open access)

A Computational Model for Coal Transport and Combustion. Quarterly Technical Progress Report, December 1, 1992--February 28, 1993

In the period of December 1, 1992 to February 28, 1993, further progress was made in using the thermodynamically consistent, rate dependent model for turbulent two-phase flows analysis. The effect of particle Reynolds number on variations of the fluctuation kinetic energy with the solid volume fraction for the special case of a simple shear flow was analyzed. Additional results for the application of the kinetic model for rapid flows of granular materials, which includes frictional losses were obtained. The velocity profile for granular gravity flow down an inclined chute, including slip velocity at the wall were obtained, and the results were compared with the data of Drake and Shreve and Johnson et al. The computational model for rapid granular and two-phase flows in complex geometries was further developed. The discrete element scheme was used and the granular flow down a chute was analyzed. The results are compared with the experimental data model prediction of Savage, and the simulation results of Campbell and Brennen. The experimental monolayer simple shear flow device was modified to allow for shearing of 12 mm multi-color glass particles. The device was reassembled and made fully operational. Sample videos of the granular motions are obtained. Developing a …
Date: May 1, 1993
Creator: Ahmadi, Goodarz
Object Type: Report
System: The UNT Digital Library
Current loop decay in Rutherford-type cables (open access)

Current loop decay in Rutherford-type cables

Recent measurements of superconducting panicle accelerator magnets made of multistrand Rutherford-type cable have shown that the magnetic field and its main harmonics oscillate along the magnet axis with a wavelength nearly equal to the cable transposition. It was also observed that, at low transport current, the periodic magnetic pitch length. It was also observed that, at low transport current, the periodic magnetic field patterns can persist without any significant decay for more than 12 hours. The coincidence of the wavelength of the magnetic field oscillations with the cable transposition pitch suggests that slowly decaying current loops exist in the cable even at zero transport current. These loops consist of currents flowing along the cable through one set of strands and returning through another set of strands. In this paper, we consider the process of current loop decay in a Rutherford-type cable.
Date: May 1, 1993
Creator: Akhmetov, A. A.; Devred, A.; Schermer, R. I. & Mints, R. G.
Object Type: Article
System: The UNT Digital Library
Removal of CO{sub 2} from flue gases by algae. Technical report, December 1, 1992--February 28, 1993 (open access)

Removal of CO{sub 2} from flue gases by algae. Technical report, December 1, 1992--February 28, 1993

The studies reported here confirmed our preliminary observations that Botryococcus braunii can tolerate and grow well in flue gas CO{sub 2} concentrations of 10 to 15%, and produce oil. The highest extracted oil was observed in 10% CO{sub 2} enriched air. Initial pH of the medium at or near 10 pH is favorable to cell growth probably by stimulating the CO{sub 2} solubilization in the medium. This is also indicated in Botryococcus braunii growth and oil formation in NaHCO{sub 3} added medium. The lack of growth in Na{sub 2}CO{sub 3} containing media was probably due to high pH. The CaCO{sub 3} precipitation from the CA{sup ++} gelled alginate beads indicate the need for alternative immobilization systems. But the attachment of the Botryococcus braunii cells to the bottom inner surfaces of the photobioreactors may eliminate the need for gel entrapment systems as the immobilization matrices. Attachment of the Botryococcus braunii cells to the bottom inner surfaces of the photobioreactors, rather than remaining in the suspension, reduces the significance of self shadowing and related liquid height (thickness) effect. The capability of Botryococcus braunii to grow in NaHCO{sub 3} solutions is very encouraging toward development of an alkaline scrubbing system for the flue …
Date: May 1, 1993
Creator: Akin, C.; Maka, A.; Pradhan, S. & Banerjee, D.
Object Type: Report
System: The UNT Digital Library
The development of in vitro mutagenicity testing systems using T-lymphocytes. Research progress report, November 1, 1992--October 31, 1993 (open access)

The development of in vitro mutagenicity testing systems using T-lymphocytes. Research progress report, November 1, 1992--October 31, 1993

This annual report describes progress in studies on hprt mutations induced by radon or Indium 111 along with the corresponding mutation frequency, cloning and molecular spectra in human T-lymphocytes. Parallel studies on the mutation susceptibility between individuals is being investigated by hprt mutation studies on ataxia telangiectasia and xeroderma pigmentosum.
Date: May 1, 1993
Creator: Albertini, R. J.
Object Type: Report
System: The UNT Digital Library
The development of in vitro mutagenicity testing systems using T-lymphocytes (open access)

The development of in vitro mutagenicity testing systems using T-lymphocytes

This annual report describes progress in studies on hprt mutations induced by radon or Indium 111 along with the corresponding mutation frequency, cloning and molecular spectra in human T-lymphocytes. Parallel studies on the mutation susceptibility between individuals is being investigated by hprt mutation studies on ataxia telangiectasia and xeroderma pigmentosum.
Date: May 1, 1993
Creator: Albertini, R.J.
Object Type: Report
System: The UNT Digital Library
Metals 2000 (open access)

Metals 2000

This strategic planning exercise identified and characterized new and emerging advanced metallic technologies in the context of the drastic changes in global politics and decreasing fiscal resources. In consideration of a hierarchy of technology thrusts stated by various Department of Defense (DOD) spokesmen, and the need to find new and creative ways to acquire and organize programs within an evolving Wright Laboratory, five major candidate programs identified are: C-17 Flap, Transport Fuselage, Mach 5 Aircraft, 4.Fighter Structures, and 5. Missile Structures. These results were formed by extensive discussion with selected major contractors and other experts, and a survey of advanced metallic structure materials. Candidate structural applications with detailed metal structure descriptions bracket a wide variety of uses which warrant consideration for the suggested programs. An analysis on implementing smart skins and structures concepts is given from a metal structures perspective.
Date: May 1, 1993
Creator: Allison, S. W.; Rogers, L. C.; Slaughter, G.; Boensch, F. D.; Claus, R. O. & de Vries, M.
Object Type: Report
System: The UNT Digital Library
Emittance growth rates for displaced beams (open access)

Emittance growth rates for displaced beams

Emittance growth rates have been previously analyzed for nonuniform beams in linear channels and for initially uniform mismatched beams in nonlinear channels. These studies were for centered beams. Additional emittance growth can arise in cases where the beam is initially displaced. The purpose of this study is to obtain growth rates for displaced beams. This work differs from studies involving random displacement of electrodes. Our analysis assumes instead that the focusing system is perfectly aligned but that the beam is initially displaced with respect to the equilibrium axis. If the focusing force is slightly nonlinear, we find a gradual transfer of the potential energy of beam displacement into kinetic energy associated with emittance growth. We present explicit results for the emittance growth distance as a function of the nonlinearity of the channel. These results will have practical importance for designers of accelerators and transport systems when setting realistic tolerances for initial beam alignment. These tolerances will depend on the nonlinearity and the length of the system.
Date: May 1, 1993
Creator: Anderson, O. A.
Object Type: Article
System: The UNT Digital Library
Investigation of physical structures and interactions at high energy. Progress report, June 1, 192--May 31, 1992 (open access)

Investigation of physical structures and interactions at high energy. Progress report, June 1, 192--May 31, 1992

This report contains discussions on the following topics: Experimental program at the Fermilab Tevatron Collider: FNAL E-740; Experimental program at the superconducting super collider: Solenoidal detector collaboration; Computation development program at Iowa State University: Batch after twilight running and parallel processing; Experimental program at the University of Hawaii: Deep underwater muon and neutrino detector; Global analysis of parton distributions; high energy direct photon production; photon fragmentation functions; single transverse-spin asymmetry; associated production of Higgs Boson at collider energies; Cronin effect in photoproduction and deeply inelastic scattering; and heavy meson production.
Date: May 31, 1993
Creator: Anderson, W. E.; Hauptman, J. M. & Qui, J.
Object Type: Report
System: The UNT Digital Library
Fiber optic spectrochemical emission sensor: Detection of volatile chlorinated compounds in air and water using ultra-thin membranes (open access)

Fiber optic spectrochemical emission sensor: Detection of volatile chlorinated compounds in air and water using ultra-thin membranes

Prior work on the fiber optic spectrochemical emission sensor called HaloSnif{trademark} has been extended to include an ultra-thin membrane which allows passage of volatile organic chlorinated compounds (VOCl). The membrane has been demonstrated to exclude H{sub 2}O during VOCl monitoring. The system is capable of measuring VOCl in gas-phase samples or aqueous solutions over a wide linear dynamic range. The lower limit of detection for trichloroethylene (TCE), perchloroethylene (PCE), carbon tetrachloride (CCl{sub 4}), and other related compounds in the gas-phase is 1 to 5 ppm{sub v/v}, and in the aqueous-phase is 5 to 10 mg/L. Waste site characterization and remediation activities often require chemical analysis in the vadose zone and in groundwater. These analyses are typically performed in analytical laboratories using widely accepted standardized methods such as gas chromatography, gas chromatography/mass spectrometry. The new developments with HaloSnif provide rapid field screening which can augment the standardized methods.
Date: May 1993
Creator: Anheier, N. C., Jr.; Olsen, K. B.; Osantowski, R. E.; Evans, J. C., Jr. & Griffin, J. W.
Object Type: Article
System: The UNT Digital Library
Nonlinear dynamics and plasma transport. Progress report, September 15, 1992--September 14, 1993 (open access)

Nonlinear dynamics and plasma transport. Progress report, September 15, 1992--September 14, 1993

This progress report details work done on a program in nonlinear dynamical aspects of plasma turbulence and transport funded by DOE since 1989. This program has been in cooperation with laboratories in theUSSR [now Russia and the Confederation of Independent States (CIS)]. The purpose of this program has been: To promote the utilization of recent pathbreaking developments in nonlinear science in plasma turbulence and transport. To promote cooperative scientific investigations between the US and CIS in the related areas of nonlinear science and plasma turbulence and transport. In the work reported in our progress report, we have studied simple models which are motivated by observation on actual fusion devices. The models focus on the important physical processes without incorporating the complexity of the geometry of real devices. This allows for a deeper analysis and understanding of the system both analytically and numerically.
Date: May 1, 1993
Creator: Antonsen, T. M. Jr.; Drake, J. F.; Finn, J. M.; Guzdar, P. N.; Hassam, A. B. & Sageev, R. Z.
Object Type: Report
System: The UNT Digital Library
Maryland controlled fusion research program. Progress report, November 1, 1992--October 31, 1993 (open access)

Maryland controlled fusion research program. Progress report, November 1, 1992--October 31, 1993

In recent years, members of the Maryland Plasma Theory Group have made significant contributions to the national fusion theory program, and, in many cases, these theoretical developments helped to interpret experimental results and to design new experimental programs. In this paper, we summarize the technical progress in four major areas of tokamak research: (a) L/H transition and edge turbulence and transport; (b) active control of micro-turbulence and transport; (c) major disruptions; and (d) the sawtooth crash.
Date: May 1, 1993
Creator: Antonsen, T. M., Jr.; Drake, J. F.; Finn, J. M.; Guzdar, P.; Hassam, A.; Liu, C. S. et al.
Object Type: Report
System: The UNT Digital Library
Sensitivity of the close-in seismic source function to rock properties. Los Alamos Source Region Program (open access)

Sensitivity of the close-in seismic source function to rock properties. Los Alamos Source Region Program

The objective of this investigation is to determine and evaluate how rock properties near the origin of an explosion influence the close-in seismic source function. This is work in progress that represents one step in the systematic investigation of parameters important in the remote identification of underground nuclear tests. In this study, the `overshoot`` and ``steady state value`` of the reduced displacement potential, and the ``corner frequency`` and ``rolloff`` of the reduced velocity potential spectrum are the properties of the source function used as principal measures of effect. A series of one-dimensional, spherically symmetric calculations are made with the computational mesh divided into six phenomenological regions. Material properties are modified in selected regions to evaluate source function sensitivities.
Date: May 1, 1993
Creator: App, F. N.
Object Type: Report
System: The UNT Digital Library
Monitored Thermal Performance Results of Second Generation Superwindows in Three Montana Residences. (open access)

Monitored Thermal Performance Results of Second Generation Superwindows in Three Montana Residences.

Simulation studies have shown that highly insulating windows with moderate solar transmittances (R values greater than 6 hr-ft[sup 2]--F/Btu and shading coefficients greater than 0.5) can outperform insulated walls on any orientation, even in a northern US climate. Such superwindows achieve this feat by admitting more useful solar heat gains during the heating season than energy lost through conduction, convection and infrared radiation. Testing of first generation superwindows in three new homes in northern Montana during the winter of 1989--1990, reported in an earlier study, indicated that the glazed areas of superwindows can in fact outperform insulated walls on obstructed off-south orientations. However, this same study also showed that further improvements in the thermal performance of window edges and frames are necessary if the entire window is to outperform an insulated wall. As a result, second generation superwindows with improved frame, edge, and glazing features were installed in these houses during the summer and fall of 1990 and these windows were monitored during the winter of 1990--1991. Results from this monitoring effort, discussed in this paper, showed that while small performance improvements may have been made with these second generation superwindows, the frame and edge still limited performance.
Date: May 1, 1993
Creator: Arasteh, D.
Object Type: Report
System: The UNT Digital Library
Impulse radar imaging for dispersive concrete using inverse adaptive filtering techniques (open access)

Impulse radar imaging for dispersive concrete using inverse adaptive filtering techniques

This publication addresses applications of a delayed inverse model adaptive filter for modeled data obtained from short-pulse radar reflectometry. To determine the integrity of concrete, a digital adaptive filter was used, which allows compensation of dispersion and clutter generated by the concrete. A standard set of weights produced by an adaptive filter are used on modeled data to obtain the inverse-impulse response of the concrete. The data for this report include: Multiple target, nondispersive data; single-target, variable-size dispersive data; single-target, variable-depth dispersive data; and single-target, variable transmitted-pulse-width dispersive data. Results of this simulation indicate that data generated by the weights of the adaptive filter, coupled with a two-dimensional, synthetic-aperture focusing technique, successfully generate two-dimensional images of targets within the concrete from modeled data.
Date: May 1, 1993
Creator: Arellano, J.; Hernandez, J. M. & Brase, J.
Object Type: Report
System: The UNT Digital Library
Performance and evaluation of gas engine driven rooftop air conditioning equipment at the Willow Grove (PA) Naval Air Station (open access)

Performance and evaluation of gas engine driven rooftop air conditioning equipment at the Willow Grove (PA) Naval Air Station

In a field evaluation conducted for the US Department of Energy (DOE) Office of Federal Energy Management Program (FEMP), the Pacific Northwest Laboratory (PNL) examined the performance of a new US energy-related technology under the FEMP Test Bed Demonstration Program. The technology was a 15-ton natural gas engine driven roof top air conditioning unit. Two such units were installed on a naval retail building to provide space conditioning to the building. Under the Test Bed Demonstration Program, private and public sector interests are focused to support the installation and evaluation of new US technologies in the federal sector. Participating in this effort under a Cooperative Research and Development Agreement (CRADA) with DOE were the American Gas Cooling Center, Philadelphia Electric Company, Thermo King Corporation, and the US Naval Air Station at Willow Grove, Pennsylvania. Equipment operating and service data as well as building interior and exterior conditions were secured for the 1992 cooling season. Based on a computer assessment of the building using standard weather data, a comparison was made with the energy and operating costs associated with the previous space conditioning system. Based on performance during the 1992 cooling season and adjusted to a normal weather year, the technology …
Date: May 1, 1993
Creator: Armstrong, P. R. & Conover, D. R.
Object Type: Report
System: The UNT Digital Library
Performance and evaluation of gas engine driven rooftop air conditioning equipment at the Willow Grove (PA) Naval Air Station. Interim report, 1992 cooling season (open access)

Performance and evaluation of gas engine driven rooftop air conditioning equipment at the Willow Grove (PA) Naval Air Station. Interim report, 1992 cooling season

In a field evaluation conducted for the US Department of Energy (DOE) Office of Federal Energy Management Program (FEMP), the Pacific Northwest Laboratory (PNL) examined the performance of a new US energy-related technology under the FEMP Test Bed Demonstration Program. The technology was a 15-ton natural gas engine driven roof top air conditioning unit. Two such units were installed on a naval retail building to provide space conditioning to the building. Under the Test Bed Demonstration Program, private and public sector interests are focused to support the installation and evaluation of new US technologies in the federal sector. Participating in this effort under a Cooperative Research and Development Agreement (CRADA) with DOE were the American Gas Cooling Center, Philadelphia Electric Company, Thermo King Corporation, and the US Naval Air Station at Willow Grove, Pennsylvania. Equipment operating and service data as well as building interior and exterior conditions were secured for the 1992 cooling season. Based on a computer assessment of the building using standard weather data, a comparison was made with the energy and operating costs associated with the previous space conditioning system. Based on performance during the 1992 cooling season and adjusted to a normal weather year, the technology …
Date: May 1, 1993
Creator: Armstrong, P. R. & Conover, D. R.
Object Type: Report
System: The UNT Digital Library
Chemical interactions between interconnect and electrode materials during sintering in solid oxide fuel cells (open access)

Chemical interactions between interconnect and electrode materials during sintering in solid oxide fuel cells

Chemical interactions and interdiffusion between the interconnect, (LaCa)CrO{sub 3} and (YCa)CrO{sub 3} and the anode, Ni{center_dot}ZrO{sub 2}, and cathode, (LaSr)MnO{sub 3} and (YCa)MnO{sub 3}, were evaluated from 1300 to 1500C. Reaction of (LaCa)CrO{sub 3} and Ni{center_dot}ZrO{sub 2} cermet resulted in the formation of NiCr{sub 2}O{sub 4} spinel, while reaction of (YCa)CrO{sub 3} and Ni{center_dot}ZrO{sub 2} resulted in the formation of both NiCr{sub 2}O{sub 4} and CaZrO{sub 3}, at all temperatures. Interactions between the chromites and manganites resulted in the formation of a solid solution. Dense reaction layers were observed near the interface of Ni{center_dot}ZrO{sub 2}/(LaCa)CrO{sub 3} and Ni{center_dot}ZrO{sub 2}/(YCa)CrO{sub 3} samples. These dense regions were enriched in calcium and chromium, resulting from liquid migration from the chromite to the anode. Nearly ideal interfaces were observed between (LaSr)MnO{sub 3} and (LaCa)CrO{sub 3}. Interactions between (YCa)CrO{sub 3} and (YCa)MnO{sub 3} resulted in the formation of a CaCrO{sub 4} rich layer along the interface.
Date: May 1, 1993
Creator: Armstrong, T. R.; Chick, L. A. & Bates, J. L.
Object Type: Article
System: The UNT Digital Library
Jet initiation thresholds of nitromethane (open access)

Jet initiation thresholds of nitromethane

The initiation criterion for nitromethane and diethylenetriamine- sensitized solutions has been established over a confined range of jet diameters, velocities, and failure diameters. The data were normalized with the failure diameter that was chemically modified, and they support the hypothesis that the failure diameter should be made part of the critical initiation function. The difference between physically- and chemically sensitized NM in promptness of initiation, as measured by corner turning distance, was not statistically significant. The diameter of the Viper jet has been characterized over a wide range of velocities.
Date: May 1, 1993
Creator: Asay, B. W.; Pauley, D. J. & Ferm, E. N.
Object Type: Article
System: The UNT Digital Library
Measurements of crystal growth kinetics at extreme deviations from equilibrium. Technical progress report, 1 September 1992--31 August 1993 (open access)

Measurements of crystal growth kinetics at extreme deviations from equilibrium. Technical progress report, 1 September 1992--31 August 1993

We have measured solute trapping of Sn in Al over a wide enough range of velocities to make a quantitative test of theory. The Continuous Growth Model of Aziz is the only one-parameter model that fits the data. We have also measured the diffusive speed - the growth rate at which interfacial partitioning is in mid-transition between equilibrium partitioning and complete solute trapping - for several solutes in A1. We have found an inverse correlation between the equilibrium partition coefficient and the diffusive speed. Taken together, these results give us heretofore unprecedented predictive capability in modeling rapid solidification processing. We have also examined theoretically short-range diffusion-limited growth, characteristic of incomplete solute trapping, and interface-limited growth, characteristic of complete solute trapping, in alloy solidification and have shown that the two regimes fall naturally out of a single unified theory of solidification.
Date: May 7, 1993
Creator: Aziz, M. J.
Object Type: Report
System: The UNT Digital Library
Measurements of crystal growth kinetics at extreme deviations from equilibrium. [Rapid solidification processing] (open access)

Measurements of crystal growth kinetics at extreme deviations from equilibrium. [Rapid solidification processing]

We have measured solute trapping of Sn in Al over a wide enough range of velocities to make a quantitative test of theory. The Continuous Growth Model of Aziz is the only one-parameter model that fits the data. We have also measured the diffusive speed - the growth rate at which interfacial partitioning is in mid-transition between equilibrium partitioning and complete solute trapping - for several solutes in A1. We have found an inverse correlation between the equilibrium partition coefficient and the diffusive speed. Taken together, these results give us heretofore unprecedented predictive capability in modeling rapid solidification processing. We have also examined theoretically short-range diffusion-limited growth, characteristic of incomplete solute trapping, and interface-limited growth, characteristic of complete solute trapping, in alloy solidification and have shown that the two regimes fall naturally out of a single unified theory of solidification.
Date: May 7, 1993
Creator: Aziz, Michael J.
Object Type: Report
System: The UNT Digital Library