| High Strain Rate Properties of Tantalum Processed by Equal Channel Angular Pressing |
AUG 2007 |
18 pages |
| Authors:
Philip J. Flater; Joel W. House; James M. O'Brien; William F. Hosford; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
|
 | Current ingot refinement and solidification techniques used in tantalum processing often result in inconsistent mechanical properties. Subsequent processing by equal channel angular pressing (ECAP) has been shown to reduce or eliminate internal structural variations as well as part-to-part variability [2]. This paper presents the effects of ECAP processing on the properties of tantalum. The materials of interest are 2.5-inch round bar tantalum supplied by H.C. Starck and Cabot Supermetals. Three ... |
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| Investigation of Superplastic Behavior in FSP 5083 Aluminum Alloy |
JUN 2007 |
65 pages |
| Authors:
Marc T. Bland; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Continuously-cast AA5083 in the form of as-cast billets 15 mm in thickness condition was subjected to friction stir processing (FSP) by five overlapping passes. The FSP utilized a tool having a pin approximately 5 mm in length, so that the process zone had a depth that was approximately one-third of the billet thickness. The solidification microstructure of the as-cast material included grains that were approximately 60 m in size as ... |
|
| Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys |
Jun-2007 |
9 pages |
| Authors:
Christopher Woodward; Mark Asta; Dallas Trinkle; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| In casting of single-crystal turbine blades for jet engines, the formation of solidification defects has become an increasingly important problem due to the rising levels of refractory elements in Ni-based superalloys. Refractory elements, which are beneficial for high-temperature mechanical properties, enhance density-driven convective instabilities underlying the formation of freckle defects in directional solidification. In support of an effort aimed at the development of validated mathematical criteria for predicting solidification-defect formation ... |
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| Directionally Solidified Multifunctional Ceramics |
DEC 2006 |
17 pages |
| Authors:
Ali Sayir; CASE WESTERN RESERVE UNIV CLEVELAND OH
|
| In order to achieve a significant increase in toughening and to retain the toughness at elevated temperatures a new multifunctional approach is proposed. The multifunctionality were achieved through directional solidification of polyphase materials comprising the load-bearing and functional phases. The functional phases include shape recovery and health monitoring. In parallel, new ideas about the load bearing phases were investigated to achieve tougher materials. |
|
| A Multi-Scale Modeling of Laser Cladding Process (Preprint) |
APR 2006 |
42 pages |
| Authors:
J. Cao; J. Choi; MISSOURI UNIV-ROLLA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| Laser cladding is an additive manufacturing process that a laser generates a melt-pool on the substrate material while a second material, as a powder or a wire form, is injected into that melt-pool. Among all laser manufacture processes, laser cladding offers the most extensive variety of possibilities to alter a component at its surface. Despite immense potentials and advancements, the process model of microstructure evolution and its coupling with macro ... |
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| Graphitized Carbon Foam with Phase Change Material |
MAR 2006 |
59 pages |
| Authors:
Angelinda D. Fedden; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| This thesis examines the transient heating and cooling responses of graphitized carbon foam infiltrated with phase change material (PCM). The carbon foam provides rapid heat transfer throughout the PCM volume, while the PCM stores the heat for later removal. The foam/PCM system was heated with a copper heating block, and then cooled with a liquid-cooled heat removal block. Infiltrating the foam with PCM significantly increased the length of time before ... |
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| Development of Metal/Ceramic Nanocomposite Powder and Consolidation to Bulk Nanocomposite Components with Retained Nanostructures |
17 NOV 2005 |
13 pages |
| Authors:
Sudipta Seal; Petya Georgieva; Keith Rea; Venkatachalapathy Viswanathan; UNIVERSITY OF CENTRAL FLORIDA ORLANDO DEPT OF MECHANICAL MATERIALS AND AEROSPACE ENGINEERING
|
| An instrument innovation has been developed that enables for the minimization of oxidation during Air Plasma Spray (APS). Oxidation is limited due to the creation of a three-part copper shroud that utilizes a custom-fit mounting plate that is affixed to the SG-100 APS plasma gun. Due to the separation of the ambient environment from the plasma flame and the particles traveling through it, this process has been deemed Shrouded Air ... |
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| Fundamental Structure-Property Relationships for High-Temperature Ceramic Composites |
MAY 2005 |
13 pages |
| Authors:
Elizabeth C. Dickey; PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This research program focused on studying interface structure and thermal compatibility stresses in several directionally solidified eutectic ceramic materials, which are candidates for high-temperature and ultra-high temperature structural materials in aerospace applications. Under this award we specifically investigated the alumina-zirconia and lanthanum hexaboride-zirconium diboride eutectic systems. High-resolution transmission electron microscopy was utilized to understand interfacial structures in these materials and x-ray diffraction was utilized to measure thermal residual stresses. A ... |
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| Structure Synthesis and Kinetics During Undercooled Liquid Solidification and Intense Plastic Deformation |
29 MAR 2005 |
19 pages |
| Authors:
John H. Perepezko; WISCONSIN UNIV-MADISON DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| At high undercooling, solidification is rapid and can result in the suppression of the usual reactions to yield amorphous phases and nonequilibrium crystalline phases with novel microstructures. In a complimentary approach, the intense deformation of an elemental layered array drives an atomic scale mixing at the interfaces to yield alloying and in some systems an amorphization reaction. Similarly, deformation of amorphous ribbons can drive instabilities that result in the development ... |
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| Effects of Process Variables and Size Scale on Solidification Microstructure in Laser-Based Solid Freeform Fabrication of Ti-6Al-4V |
AUG 2004 |
12 pages |
| Authors:
N. W. Klingbeil; S. Bontha; C. J. Brown; D. R. Gaddam; P. A. Kobryn; H. L. Fraser; J. W. Sears; WRIGHT STATE UNIV DAYTON OH
|
| This paper summarizes a combination of analytical and numerical modeling approaches which have been used to investigate the effects of process variables and size scale on solidification microstructure in laser-deposited Ti-6A1-4V. The analytical approach is based on the well-known Rosenthal solution for a moving point heat source, which provides dimensionless process maps for solidification cooling rate and thermal gradient (the key parameters controlling microstructure) as a function of laser deposition ... |
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| Advanced Processes for High-Strength Titanium Alloys |
12 JUL 2004 |
|
| Authors:
Orest M. Ivasishin; AKADEMIYA NAUK URSR KIEV METAL PHYSICSLAB
|
 | In first part of this project, double Electron Beam Melting (EBM) was investigated for melting of high-strength alpha + beta and beta titanium alloys. The following advantages, as compared to Vacuum Arc Remelting (VAR), are expected: - full dissolution of LDl due to higher temperature and longer times in melt condition; - essential elimination of HDl by means of intermediate bath' application; - employment of cheaper initial materials, such as ... |
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| A Century of Sapphire Crystal Growth |
17 MAY 2004 |
74 pages |
| Authors:
Daniel C. Harris; NAVAL AIR SYSTEMS COMMAND CHINA LAKE CA
|
| In Paris around 1890, A. V. L. Verneuil developed a flame fusion process to produce ruby and sapphire. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, which was used with little alteration for 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire by the Verneuil process. In the U.S., under government contract during World War II, ... |
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| Turbulent Mixing of Multiphase Flow |
24 MAR 2004 |
12 pages |
| Authors:
Y. -N. Young; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
|
| Mixing of multi-phase fluids is common in diverse research fields, and understanding of such an important phenomenon is useful to a range of engineering applications such as the polymer blender or control and designs of fluid processing. In this paper we adopt the phase-field modeling approach to investigate capillary induced effects on mixing. Phase-field modeling has been applied to simulation of multi-phase flow (Chella & Vinals 1996; Jasnow & Vinals ... |
|
| Resourcing Homeland Security: "The Way Ahead" |
01 MAR 2004 |
29 pages |
| Authors:
Thomas A. Horlander; ARMY WAR COLL CARLISLE BARRACKS PA
|
| When President Bush established the Department of Homeland Security (DHS) on October 8th 2001 the newest Cabinet member of the Federal Government was given the tall order of ensuring that Americans never again relive the tragedies of September 11th 2001. The resourcing implications of such an undertaking are overwhelming. The intent of this research paper is to provide a general understanding of the complexity and magnitude of resourcing homeland security ... |
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| Directionally Solidified Eutectic Ceramics; In-Situ Composites for High Temperature Structural Applications |
25 FEB 2004 |
111 pages |
| Authors:
Ali Sayir; CASE WESTERN RESERVE UNIV CLEVELAND OHDEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Eutectics are multiphase structures formed by the cooperative growth of two or more phases. Although the internal structure can vary widely, the development of continuous rods or plates in a matrix can be achieved and, within limits, can be controlled or "tailored" through directional solidification. The eutectic architecture of a continuous reinforcing phase within a higher volume phase or matrix, can be described as a naturally occurring in-situ composite. In-situ ... |
|
| Oxygen Effects on Glass Formation of Plasma Arc Sprayed Cu47Ti33Zr11Ni8Si1 Surface Coatings |
2004 |
5 pages |
| Authors:
D. J. Sordelet; M. F. Besser; AMES LAB IA
|
| A series of thermal spray experiments were performed to produce Cu47Ti33Zr11Ni8Si1 coatings from gas atomized powders synthesized with oxygen contents ranging from 0.125 to 0.79 wt.%. The amount of oxygen increased with decreasing particle size, which suggests the oxide is present as a surface film. Surface coatings were deposited using plasma arc spraying (PAS) in air and in an argon environment within an environmental chamber. The amount of amorphous phase ... |
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| Materials Science Aspects of Weld Corrosion |
29 OCT 2003 |
|
| Authors:
D. L. Olson; A. N. Lasseigne; M. Marya; B. Mishra; G. Castro; COLORADO SCHOOL OF MINES GOLDEN
|
| Corrosion is an environmentally assisted damage that professionals face daily, particularly with welded structures. Fusion welds result from solidification and solid-state transformations induced by well-localized thermal cycles. A fusion weld joint inherently exhibits an irregular surface as well as gradients in chemical composition, microstructure, properties and residual stress, depending upon process parameters and part geometry. This article analyzes the roles of surface topography, alloy chemical compositional variation, hydrogen distribution, and ... |
|
| The International Conference on Nanostructured Materials (6th) - NANO 2002 Held in Orlando, Florida on June 16-21, 2002 |
20 AUG 2003 |
8 pages |
| Authors:
Bernard H. Kear; RUTGERS - THE STATE UNIV PISCATAWAY NJDEPT OF CERAMIC ENGINEERING
|
| General topical areas and categories included: 1. Theoretical modeling and computer simulations of nanostructures and properties 2. Synthesis and processing thin films and layers 3. Synthesis and processing solidification technique 4. Synthesis and processing-mechanical methods 5. Synthesis and processing-nanocrystallization of amorphous alloys 6. Synthesis and processing- electrodeposition, other physical, chemical, and biological methods 7. Nanocomposite (metal-metal, metal-ceramic, biocomposites) 8. Structure and characterization 9. Crystallography of nanocrystalline and nanoquasicrystalline material 10. ... |
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| Processing, Microstructures, and Properties of Nb-Based Metal/Silicide Alloys |
01 JUL 2003 |
42 pages |
| Authors:
Madan G. Mendiratta; UES INC DAYTON OH
|
| The Nb-Ti-Cr-Si-X alloys (X-Ht, Al, Sn, Fe, Ge) consisting of the solid solution Nb phase (Nb,s) in equilibrium with intermetallic phases ((NbTi) 5Si3 and Cr2Nb) are potential candidates as hot-section materials for jet engines. The processing-microstructure-mechanical property relationship and damage/fracture mechanisms of these alloys have been investigated. Processing methods have included induction skull melting, rapidly solidified powder production by rotating electrode and gas-atomization processes, and thermomechanical processing involving hipping and ... |
|
| Simulations of the Freezing of Jet Fuel |
MAR 2003 |
13 pages |
| Authors:
J. S. Ervin; D. Atkins; C. Obringer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
|
| The objective of this research is to obtain images of the freezing of hydrocarbon fuels within a simple flow to assist understanding of the interaction between the flow and phase change dynamics. Another objective is to describe a computational model of the freezing process. JPTS, Jet A, and additized Jet A samples were cooled in a rectangular, aluminum chamber with quartz viewing windows. Images and surface temperatures were recorded during ... |
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| Ferromagnetic shape Memory of Nanostructure Fe-Pd Alloy: The Texture Observation Study by Laser and Electronic Microscopes |
2003 |
6 pages |
| Authors:
T. Okazaki; T. Kubota; Y. Furuya; S. Kajiwara; T. Kikuchi; NATIONAL INST FOR MATERIALS SCIENCE IBARAKI TSUKUBA (JAPAN)
|
| Ferromagnetic shape memory Fe-29.6at%Pd alloy ribbon (about 60 micrometer thickness) prepared by the rapid solidification melt-spinning method has a large magnetostriction of 1.0 x 10(exp -3) when a magnetic field of 10 kOe is applied normal to the ribbon surface at room temperature. The strain induced by magnetic field is caused by the conversion of variants in the martensite phase and increases with temperature and has a maximum at phase ... |
|
| Joining of Gamma Titanium Aluminides |
SEP 2002 |
114 pages |
| Authors:
William A. Baeslack III; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| This report summarizes, interprets and comparatively discusses the results of research and development performed on the joining of gamma titanium aluminides during the past two decades. Although organized and presented by joining process, many of the observations made and relationships developed, particularly those regarding the weldability and welding metallurgy of gamma titanium aluminides, are broadly applicable. Generally, the basic welding processes and techniques utilized in the fusion and solid -state ... |
|
| Symposium T "Statistical Mechanical Modeling in Materials Research" |
13 AUG 2002 |
19 pages |
| Authors:
Maria Bartelt; James Evans; Alain S. Karma; Salvatore Torquato; Dietrick Wolf; MATERIALS RESEARCH SOCIETY WARRENDALE PA
|
| Symposium T Objective: To showcase recent developments in statistical mechanical modeling of non-equilibrium stmctures and processes in materials (including film growth, solidification processes, and bulk defect dynamics). |
|
| Metals Processing/Processing Science. Work Order Directive (WUD) 49 |
MAY 2002 |
40 pages |
| Authors:
S. L. Semiatin; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| A wide range of research related to the deformation, solidification, and vapor processing of materials of importance to the Air Force was conducted under this Work Unit Directive. The primary theme of all of the research was to establish the physics of materials behavior during processing and to exploit this knowledge to improve existing processes and develop new processes. The important results are discussed in the following sections on intermetallic ... |
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| New Welding Consumables and Practice for Highly Portable Field Repair |
20 DEC 2001 |
31 pages |
| Authors:
D. L. Olson; COLORADO SCHOOL OF MINES GOLDEN CENTERFOR WELDING JOINING AND COATINGS RESEARCH
|
| New welding consumables and practice for weld repair and extended service life were investigated. Exothermally assisted arc welding was successfully accomplished with both SMA and self-shielded FCA welding consumables on steels and the optimum range of exothermic additions and welding parameters was determined Metal powder-filled core aluminum wires were produced which, on welding, promote grain refinement in aluminum weld deposits. Grain refinement in aluminum welds is directly related to weldability ... |
|
| Rapid-Solidification Effect on Magnetostriction in Iron-based Ferromagnetic Shape Memory Alloy |
NOV 2001 |
|
| Authors:
Yasubumi Furuya; Takeshi Kubota; Teiko Okazaki; Mitsutaka Sato; Manfred Wuttig; MARYLAND UNIV COLLEGE PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Fe-29.6at%Pd ferromagnetic shape memory alloy (FSMA) ribbon formed by rapidly solidified, melt-spinning methods is expected to be useful as a new type of material which shows giant magnetostriction as well as quick response. The giant magnetostriction in the rolling direction depends strongly on applied magnetic-field direction and has a maximum value of 8 x 10(exp -4) when the field is normal to the surface. This phenomenon is caused by the ... |
|
| Superconductivity of Embedded Lead Nanoparticles in Metallic and Aamorphous Matrices |
NOV 2001 |
|
| Authors:
K. Chattopadhyay; V. Bhattacharya; A. P. Tsai; INDIAN INST OF SCIENCE BANGALORE
|
| Nanodispersed lead in metallic and amorphous matrices was synthesized by rapid solidification processing. The optimum microstructure was tailored to avoid percolation of the particles. With these embedded particles it is possible to study quantitatively the effect of size on the superconducting transition temperature by carrying out quantitative microstructural characterization and magnetic measurements. Our results suggest the role of the matrices in enhancement or depression of superconducting transition temperature of lead. ... |
|
| Solidification of Undercooled Liquids; Structure Synthesis and Kinetics |
10 JUN 2001 |
54 pages |
| Authors:
John H. Perepezko; WISCONSIN UNIV-MADISON
|
| When a liquid is subdivided into a fine droplet dispersion in order to isolate nucleation catalysts, substantial undercooling may be observed before solidification as demonstrated by thermal analysis in the current work. At high undercooling, alloy solidification is rapid and can result in the suppression of the usual reactions to yield amorphous phases and nonequilibrium crystalline phases with distinct and novel microstructures. In a complimentary approach, the intense deformation of ... |
|
| Magnetic and Microstructural Aspects of the Bulk Metallic Glassy Materials Nd60Fe30Al10 |
APR 2001 |
|
| Authors:
N. H. Dan; N. X. Phuc; V. H. Ky; N. M. Hong; N. Chau; IOWA STATE UNIV AMES
|
| The ferromagnetic bulk metallic glass (BMG) Nd60Fe30Al10 system exhibits extremely large coercivities at low temperature and moderate coercivities near room temperature. The magnetic hardness, as best evidenced by the onset of magnetic irreversibility, was studied in bulk suction-cast and melt-spun alloys with the nominal composition Nd60Fe30Al10. Systematic x-ray diffraction studies of the degree of crystallinity performed as a function of position within the bulk suction-cast samples is found to correlate ... |
|
| Studies of Transport Phenomena and Their Effect on Weld Quality in Laser Beam Welding |
31 MAR 2001 |
25 pages |
| Authors:
Hai-Lung Tsai; MISSOURI UNIV-ROLLA DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The objective of this project was to study complicated transport phenomena (laser-material interaction, heat transfer, and molten metal fluid dynamics) and their effect on weld quality in laser beam welding. The study investigated the formation of keyholes, keyhole dynamics, and possible weld defects caused by keyhole instability. A mathematical model based on continuum formulation (for handling metal flow during alloy melting/solidification) and volume-of-fluid (for handling free surfaces) was successfully developed ... |
|
| Investigation of the Laser Material Interaction Regimes during Thermal and Compositional Superposition in Laser Surface Improvement |
18 DEC 2000 |
39 pages |
| Authors:
Mary H. McCay; John Hopkins; TENNESSEE UNIV SPACE INST TULLAHOMA
|
| The objectives of the research are to 1) understand the reactions occurring within the indexed and surrounding regions as a result of the thermal and compositional cycling experienced during the formation of a laser surface modified layer, and 2) to evaluate the process kinetics, solidification and growth morphologies based on thermodynamic and heat conduction considerations. In order to accomplish these objectives, the laser surfacing process was divided into three significant ... |
|
| Interdendritic Fluid Flow Effects on Single Crystal Grain Defects |
26 OCT 2000 |
98 pages |
| Authors:
R. A. Overfelt; AUBURN UNIV AL SPACE POWER INST
|
| This research project has been investigating the phenomenon of grain defect formation in nickel-base superalloys. Cylindrical samples of the nickel- based multicomponent alloy PWA 1484 were produced by Howmet Corporation. Utilization of this alloy enabled the application in this research of previous data on this alloy on dendrite arm spacings and thermophysical properties. Samples were re-solidified under carefully controlled laboratory conditions to modify the ... |
|
| An Evaluation of Solidification/Stabilization for Sediments from the Puget Sound Naval Shipyard |
SEP 2000 |
38 pages |
| Authors:
Michael G. Channell; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB
|
| Contaminated sediments from the Puget Sound Naval Shipyard were evaluated using solidification/ stabilization technologies to determine if the material could have beneficial uses. Varying ratios of four binders (Portland cement, kiln dust, lime/fly ash, and Portland cement/fly ash) were evaluated on the material to determine if soil-like properties could be obtained from the sediment. Physical, chemical, and contaminant leaching tests were performed on the ... |
|
| An Evaluation of Solidification/Stabilization for Sediments from the Puget Sound Naval Shipyard |
SEP 2000 |
38 pages |
| Authors:
Michael G. Channell; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB
|
| Contaminated sediments from the Puget Sound Naval Shipyard were evaluated using solidification/stabilization technologies to determine if the material could have beneficial uses. Varying ratios of four binders (Portland cement, kiln dust, lime/fly ash, and Portland cement/fly ash) were evaluated on the material to determine if soil-like properties could be obtained from the sediment. Physical, chemical, and contaminant leaching tests were performed on the untreated ... |
|
| Stimulated Heterogeneous Nucleation of Supercooled Liquid H2 Droplets |
09 JUL 2000 |
9 pages |
| Authors:
E. L. Knuth; S. Schaper; J. P. Toennies; MAX-PLANCK-INST FUER STROEMUNGSFORSCHUNG GOETTINGEN (GERMANY F R)
|
| The properties of H(2) droplets formed by condensation in a supersonic freejet were probed by the capture and coagulation of CO molecules for the purpose of determining whether the droplets are liquid or solid. The CO was introduced into the H(2) droplets by passing the droplet beam through a scattering chamber containing CO at room temperature and various pressures. Reduction of droplet size as a result of droplet collisions with ... |
|
| Soil Washing and Solidification/Stabilization Work Implementation Plan -Draft Final |
JUN 2000 |
415 pages |
| Authors:
URS GREINER INC SACRAMENTO CA
|
| This Soil Washing and Solidification/ Stabilization Work Implementation Plan has been prepared as a part of the overall McClellan Air Force Base (AFB) remediation program. This document outlines the field activities required to conduct a treatability study assessing the viability(e.g. ,cost and performance of the two remediation technologies to clean designated contaminated soils at McClellan AFB. Non-VOC soils to be treated contain various heavy metals ... |
|
| Sol-Gel Stabilization of Heavy Metal Waste |
FEB 2000 |
22 pages |
| Authors:
Donald Cropek; Patricia Kemme; Jean Day; JOse Barrios; CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL
|
| The Army is continually faced with the disposal or treatment of media contaminated with heavy metals such as lead, chromium, and cadmium. The types of media are varied and include soils, ashes, and sludges. Waste having a leachable metal concentration above the Toxicity Characteristic Leaching Procedure limit established by the U.S. Environmental Protection Agency can be treated to render it non-hazardous. Several stabilization/solidification (S/S) processes are used for ... |
|
| Eutectica V |
2000 |
|
| Authors:
METALLURGICAL ACADEMY OF UKRAINE DNIPROPETROVSK
|
| The Final Proceedings for Eutectica V, 12 June 2000 - 14 June 2000. This is a focused metallurgical conference. Topics include atomic structure of eutectic melt; influence of cluster structure of eutectic melt on kinetic of eutectic solidification; mechanism and atomic kinetics of eutectic solidification; directional solidification of eutectic alloys; three-dimensional models of eutectic grains; inoculation and modification of eutectic alloys; eutectic alloys properties; and new eutectic type alloys. ANNOTATION: ... |
|
| Crystal Preparation of Ni-Mn-Ga Alloys |
31 DEC 1999 |
16 pages |
| Authors:
Thomas A. Lograsso; IOWA STATE UNIV AMES
|
| Partial evaluation of the liquidus diagram of Ni-Mn-Ga by thermal analysis and microstructural evaluation has determined that the primary solidification surface for the Heusler alloy phase exists over a wide range of compositions. The primary solidification surface falls modestly in temperature with either increasing Mn or Ga concentrations. The composition, Ni50Mn25Ga25, melts incongruently over a temperature range of approximately 18 deg C. The small ... |
|
| The National Shipbuilding Research Program: Contaminated Sediment Management Guide for NSRP Shipyards. Appendix 5: Treatment Technologies |
22 OCT 1999 |
416 pages |
| Authors:
NATIONAL STEEL AND SHIPBUILDING CO SAN DIEGO CA
|
| The United States Environmental Protection Agency (EPA) estimates that about 10 percent of the sediment underlying U.S. lakes, rivers, and bays is sufficiently contaminated with toxic chemicals to pose potential risks. EPA began documenting the extent and severity of sediment contamination through surveys conducted in 1983 and 1987. The surveys found that heavy metals and metalloids, PCBs, pesticides, and polycyclic aromatic hydrocarbons (PAHs) are the most frequently reported contaminants in ... |
|
| Phase Stability and Microstructural Design in High Temperature (Mo,Nb)- Si-B Alloys |
15 OCT 1999 |
62 pages |
| Authors:
John H. Perepezko; WISCONSIN UNIV-MADISON DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The challenges of a high-temperature (T> 1400 deg C) environment impose severe constraints on materials selection in terms of melting temperature, oxidation resistance and structural functionality. In order to satisfy these criteria refractory metal silicides that can develop adherent SiO2 oxidation layers emerge as the most attractive candidates However, multiphase microstructure designs must be applied to address the toughening and strengthening issue that must be resolved for the use of ... |
|
| Numerical Methods for Solidification Processes in Materials Science |
31 JUL 1999 |
10 pages |
| Authors:
John A. Strain; CALIFORNIA UNIV BERKELEY DEPT OF MATHEMATICS
|
| Our overall goal is to develop, implement and transfer accurate new numerical methods for solving the moving interface problems of solidification and crystal growth. We have several specific objectives: (1) Combine fast algorithms, level set techniques, adaptive refinement and data structures to develop and implement accurate, efficient and general new methods for moving sharp interfaces. (2) Develop a modular level set code for transfer to ... |
|
| Copper Electrode Degradation Due to the Resistance Welding of Aluminum. A Trident Scholar Project Report, No. 267 |
03 MAY 1999 |
70 pages |
| Authors:
James A. Schroeder; NAVAL ACADEMY ANNAPOLIS MD
|
| This Trident research project focuses on increasing the life of copper electrodes used in the resistance welding of aluminum work pieces employed in the automotive and aerospace industries. When the copper and aluminum make contact at the interface, there is some undesirable mixing which results in the formation of a copper-aluminum eutectic phase. The welding temperature is high enough to melt the aluminum, but the ... |
|
| 75 Micron YAG-Alumina Eutectic Fiber |
14 JAN 1999 |
89 pages |
| Authors:
Joseph M. Collins; SAPHIKON INC MILFORD NH
|
| Crystal growth experiments were conducted to test the application of the Edge-defined Film- fed Growth (EFG*) technique to the growth of 75 mm single crystal yttrium aluminum garnet - alumina eutectic fibers (YAE) as well as off- eutectic and additive-modified eutectic fibers. The additive modifiers were selected to weaken the interface between the YAG and alumina phases and toughen the material. In combination with the off ... |
|
| Synthesis of Ceramics from Solutions: Functionally Graded Composites, Nanocomposites and Single Crystal Thin Films; Annual Technical Reports 12 Through 16 with a Summary |
JAN 1999 |
80 pages |
| Authors:
Fred F. Lange; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| This program has emphasized two topics: (1) the crystallization of metastable, solid-solution structures, their partitioning into equilibrium structures and compositions, and the role of the metastable phase and its partitioning on forming unique, nanometer microstructures important to the mechanics of structural ceramics and their composites, and (2) the formation of single crystal thin films via spin coating single crystal substrates with solution precursors. Results for the first topic are new, ... |
|
| iMAST Quarterly, Number 2, 1999 |
Jan-1999 |
10 pages |
| Authors:
Timothy J Eden; APPLIED RESEARCH LABORATORY STATE COLLEGE PA
|
| In this issue of our iMAST newsletter we are featuring the Materials Science Division of ARL. Dr. Tim Eden, has provided us with an article on spray metal forming. This unique technology promises to provide some unique manufacturing opportunities through the development of high-temperature, high-strength aluminum alloys. Navy ManTech and iMAST recently participated in Tech Trends 2000, a Mid-Atlantic consortia of industry, academia, and government. The event was presented by ... |
|
| Fundamental Structure-Property Relationships for High-Temperature Ceramic Composites |
1999 |
9 pages |
| Authors:
Elizabeth C. Dickey; KENTUCKY UNIV LEXINGTON DEPT OF MATERIALS AND SCIENCE ENGINEERING
|
| Directionally-solidified oxide eutectics such as alumina-YAG and alumina-zirconia show promise as high-temperature structural materials because of their high temperature strength and creep resistance. 1-5 Compatibility constraints at the internal interfaces between the two constituent phases can lead to residual stresses upon thermal cycling and elastic interaction stresses under applied loads. The magnitudes and distributions of these stresses have important ramifications for the mechanical behavior of the composites. Here we investigate ... |
|
| The Mechanisms of Creep Resistance of Advanced Directionally Solidified Eutectics: Experiments and Modeling |
1999 |
46 pages |
| Authors:
Ali S. Aragon; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
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| The creep resistance of the directionally solidified ceramic eutectics of alumina/cubic zirconia was studied experimentally in the 1200-1520 C, and 100-275 Mpa stress range, with associated TEM and SEM microscopy, as a generic example of ceramic eutectics. Additional computer simulations were done both at the atomic level and by FEM methods to study: (a) the core structure of pyramidal edge dislocations in alumina that can only climb but not glide; ... |
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| Process for Making Superplastic Steel Powder and Flakes. |
01 DEC 1998 |
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| Authors:
Jack D. Ayers; OFFICE OF THE SECRETARY OF THE NAVY WASHINGTON DC
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| In a process for making superplastic steel powder or flakes, molten steel is rapidly solidified to form a solidified material comprising substantially single-phase austenitic steel powder or flakes having a grain size of no greater than about 2 micrometers. The powder or flakes are heated at a temperature of 300 deg C. to 600 deg C. to produce superplastic steel comprising a mixture of ferrite steel and at least one ... |
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| In-Situ Nondestructive Examination of Weld Penetration |
09 NOV 1998 |
70 pages |
| Authors:
Bryan A. Chin; AUBURN UNIV AL
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| The objective of this program is to develop infrared sensing techniques to monitor and control welding penetration in gas tungsten arc and submerged arc welding processes used by the US Navy in the construction of ships. The infrared sensor will provide in-situ, nondestructive weld quality information that can be used to correct depth of penetration prior to solidification of the molten metal pool. In this project the changes in surface ... |
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