| Exploring the Fundamental of Fatigue in Composites: Opportunities using X-Ray Computed Tomography Imaging |
01 Oct 2012 |
85 pages |
| Authors:
Serafina C Garcea; S M Spearing; Ian Sinclair; SOUTHAMPTON UNIV (UNITED KINGDOM)
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 | The aim of this work emerges from the need to understand damage mechanisms in composite materials, in terms of onset, growth and propagation, and assess fatigue life behavior, using advanced computed tomography techniques. X-ray computed tomography (XCT) has become extremely useful for material science and structural materials studies, due to its capability to allow 3-D reconstruction of the specimen with high resolution, facilitating accurate microstructural and micromechanical characterization of materials. ... |
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| LRRK2 Mediated Changes in TAU Phosphorylation |
Oct 2012 |
9 pages |
| Authors:
R J Nichols; PARKINSONS INST SUNNYVALE CA
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| The gene encoding the protein kinase LRRK2 is the most frequently mutated gene in familial Parkinson's disease (PD). The microtubule associated protein Tau is a pathological component of Alzheimer's disease and genome wide associations studies implicate Tau in PD. In several mouse models it has been shown that Tau exhibits a LRRK2 dependent change in phosphorylation status. The confluence of evidence that these two disease proteins may intersect in disease ... |
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| Comprehensive Study of Plasma-Wall Sheath Transport Phenomena |
10 Sep 2012 |
21 pages |
| Authors:
Mitchell L Walker; Michael Keidar; William J Ready; Julian J Rimoli; Greg Thompson; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
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| The research effort aims to determine the fundamental transport properties (mass, charge, and energy) within the plasma sheath, and determine the relationship between plasma properties and wall surface modification as a function of wall material. Investigators from the Georgia Institute of Technology (GT), University of Alabama (UA), and George Washington University (GWU) have begun a comprehensive, integrated, multidisciplinary study on the nature and transport properties of the interaction between plasma ... |
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| Demonstration of Shear Localization in Ultrafine Grained Tungsten Alloys via Powder Metallurgy Processing Route |
Sep 2012 |
36 pages |
| Authors:
Brady Butler; Eric Klier; Daniel Casem; Ajmer Dwivedi; Micah Gallagher; Judy Hays; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Mechanical properties and deformation characteristics are very closely linked to the underlying microstructure of a material. As the grain size of a metal is pushed to ultrafine (1000 nm) and nano (100 nm) length-scales, there is often a fundamental shift in the deformation mechanisms of these materials. In particular, tungsten and tungsten alloys have been shown to deform by shear localization as opposed to stable plastic flow when their grain ... |
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| Constitutive Analysis of High-Temperature Deformation Behavior of Fine- and Coarse-Grained Two-Phase Titanium Alloys |
15 Aug 2012 |
34 pages |
| Authors:
Taekyung Lee; Chong S Lee; POHANG UNIV OF SCIENCE AND TECHNOLOGY (REPUBLIC OF KOREA) DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The present work investigated high-temperature deformation behavior (flow curve, strain rate sensitivity, deformation mode) in Ti-5Al-4V alloys using both Strain Rate Jump (SRJT) and Load Relaxation (LRT) Tests. The disparity in high temperature plasticity was observed by directly comparing two groups of results, and elucidated on the basis of microstructural evolution and semi-constitutive and quantitative analysis called internal-variable analysis. Stress-strain rate plots determined from SRJT and LRT were in good ... |
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| Development and Application of Acoustic Metamaterials with Locally Resonant Microstructures |
02 Aug 2012 |
33 pages |
| Authors:
C T Sun; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
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| Waves cannot propagate without attenuation in elastic solids with negative mass density or modulus. This briefing looks at the effect in metamaterials. |
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| Microstructure-Sensitive HCF and VHCF Simulations (Preprint) |
Aug 2012 |
44 pages |
| Authors:
Craig Przybyla; William Musinski; Gustavo Castelluccio; David L McDowell; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| This paper provides some background and historical review of how microstructure-sensitive finite element simulations can play a role in understanding effects of stress amplitude, R-ratio, and microstructure on fatigue crack formation and early growth at notches, including pores and non-metallic inclusions for Ti alloys and Ni-base superalloys. Fatigue indicator parameters (FIPs) are computed over finite volumes that relate to processes of fatigue crack formation and early growth at the scale ... |
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| Formation of Equiaxed Alpha and Titanium Nitride Precipitates in Spark Plasma Sintered TiB/Ti-6Al-4V Composites (Preprint) |
Aug 2012 |
9 pages |
| Authors:
P Nandwana; R Banerjee; J Y Hwang; M Y Koo; S H Hong; J Tiley; UNIVERSITY OF NORTH TEXAS DENTON DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Spark plasma sintered TiB/Ti-6Al-4V composites have been characterized using scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). As-SPS processed composites exhibit a more refined distribution of equiaxed alpha precipitates as compared to arc-melted composites containing similar volume fraction of TiB precipitates. Additionally, SPS processed composites also show a highly refined distribution of TiN precipitates, as revealed by TEM studies. |
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| Quantifying the Effect of 3D Spatial Resolution on the Accuracy of Microstructural Distributions (PREPRINT) |
Aug 2012 |
11 pages |
| Authors:
Michael D Uchic; Michael Groeber; Megna Shah; Gregory Loughnane; Raghavan Srinivasan; Ramana Grandhi; Matthew Riley; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS DIV
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| The choice of spatial resolution for experimentally-collected 3D microstructural data is often governed by general rules of thumb. For example, serial section experiments often strive to collect at least ten sections through the average feature-of-interest. However, the desire to collect high resolution data in 3D is greatly tempered by the exponential growth in collection times and data storage requirements. This paper explores the use of systematic down-sampling of synthetically-generated grain ... |
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| Strengthening and Plastic Flow of Ni3Al Alloy Microcrystals (Preprint) |
Aug 2012 |
47 pages |
| Authors:
D M Dimiduk; M D Uchic; P A Shade; C Woodward; S I Rao; G B Viswanathan; E Nadgorny; S Polasik; D Norfleet; M Mills; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS DIV
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| Ni3Al alloys exhibit unique deformation characteristics at small scales that are tied to their unique dislocation core structures. The present work examines microcrystal strengthening and flow for a binary Ni3Al alloy and two alloys containing -0.25 % Hf and -1.0 % Ta, and evaluates their response relative to known dislocation mechanisms for this material and sample size effects in other materials. The work includes analysis of the flow-stress anomaly mechanisms, ... |
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| Bulk Nanocomposite LaCo5/LaCo13 Magnets (POSTPRINT) |
Aug 2012 |
5 pages |
| Authors:
Yuhui Shen; Zafer Turgut; Meiqing Huang; John Horwath; DAYTON UNIV OH RESEARCH INST
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| The effects of processing parameters and composition on the magnetic properties and microstructure of nanocrystalline La-Co-based hard magnetic materials were investigated. Bulk nanocomposite LaCo5/LaCo13 magnets were fabricated by mechanical alloying of LaCo5 and La2Co7 powder mixtures and subsequent hot pressing at 580-810 deg C. A high coercive field (Hc) of over 16 kOe with a smooth demagnetization curve was obtained in a composition range of 25-30 wt. % La2Co7 when ... |
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| Probabilistic Framework for Prediction of Material Property Distributions from Small Microstructural Models (Preprint) |
Aug 2012 |
18 pages |
| Authors:
Patrick Golden; Reji John; Daniel M Sparkman; Jr Millwater Harry R; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS DIV
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| A probabilistic framework for prediction of material property distributions from small scale (i.e. 2-grain) models is proposed. Monte Carlo Simulation and kernel density estimation are used to estimate the material property distribution of a grain boundary with a 2-grain model. Extreme value and order statistics are then employed to estimate the distribution of larger microstructure models. An example of the methodology is presented for identifying the applied uniaxial stress at ... |
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| S-Layer Architectures: Extending the Morphogenetic Potential of S-Layer Protein Self Assembly |
11 Jul 2012 |
46 pages |
| Authors:
Dietmar Pum; Uwe B Sleytr; UNIVERSITY OF NATURAL RESOURCES AND APPLIED LIFE SCIENCES VIENNA (AUSTRIA)
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| Nature has developed a broad range of nanometer scale architectures based on the self-assembly of molecular building blocks. An outstanding example has been optimized by nature is Crystalline bacterial surface layers, termed S-layers. Based on the detailed knowledge about S-layer proteins, the fabrication of three-dimensional hollow S-layer protein cages was defined as the main objective of this project. S-layers are the most commonly observed cell surface structures in prokaryotic organisms ... |
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| Multi-Scale Microstructure and Mechanical Properties of High Carbon Eutectic Tantalum Carbide Reinforced with Carbon Nanotubes |
02 Jul 2012 |
35 pages |
| Authors:
Arvind Agarwal; FLORIDA INTERNATIONAL UNIV MIAMI
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| The overall objective was to develop multiwall carbon nanotube (CNT) reinforced TaC composite with an understanding of mechanical and oxidation properties. Spark plasma sintering was employed to consolidate TaC reinforced with nano B4C and carbon nanotubes. TaC and TaC-1 wt.% B4C powders were consolidated using spark plasma sintering (SPS) at 1850 oC and varying pressure of 100, 255 and 363 MPa. Addition of B4C leads to an increase in the ... |
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| Plastic Flow and Microstructure Evolution During Thermomechanical Processing of a PM Nickel-Base Superalloy (Preprint) |
Jul 2012 |
54 pages |
| Authors:
S L Semiatin; K E McClary; A D Rollett; C G Roberts; E J Payton; F Zhang; T P Gabb; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| Plastic flow and microstructure evolution during sub- and super- solvus forging and subsequent supersolvus heat treatment of the powder-metallurgy superalloy LSHR (low-solvus, high-refractory) were investigated to develop an understanding of methods that can be used to obtain a moderately-coarse gamma grain size under well-controlled conditions. To this end, isothermal, hot compression tests were conducted over broad ranges of temperature (1144 - 1450K, or 871 - 1177 degrees C) and constant ... |
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| A Comparative Study of MgY Zn Rod Produced by Different Routes Using Severe Plastic Deformation |
Jul 2012 |
7 pages |
| Authors:
Rimma Lapovok; Yuman Zhu; Jian-Feng Nie; Yuri Estrin; Suveen N Mathaudhu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Ternary Mg Y Zn alloys have attracted considerable attention due to their excellent mechanical properties and unique microstructures. Microstructural variation and the resulting mechanical properties can be affected by various processing routes, particularly those involving severe plastic deformation of a cast billet. The following approach was used in this work to perform a comparative study: Cast Mg92Y4Zn4 billet was subjected to severe plastic deformation by three different routes, namely ECAP, ... |
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| Low Temperature Superplasticity of Ti-6Al-4V Processed by Warm Multidirectional Forging (Preprint) |
Jul 2012 |
8 pages |
| Authors:
S L Semiatin; G A Salishchev; E A Kudrjavtsev; S V Zherebtsov; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS DIV
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| Multidirectional forging has been developed to produce an ultrafine-grain (UFG) microstructure in the two-phase titanium alloy Ti-6Al-4V. A microstructure with a grain size of 135 nm was attained, enabling low-temperature superplasticity (LTSP) at 550 degrees Celsius. A total elongation of 1000% and strain-rate-sensitivity coefficient m=0.47 were obtained at the optimal strain rate of 2x10(-4) s(-1). Important features of the microstructure and superplastic behavior of the alloy are summarized in the ... |
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| Intermetallic Growth and Interdiffusion in the Mg-Nd System |
Jul 2012 |
7 pages |
| Authors:
Sarah Brennan; Katrina Bermudez; Yongho Sohn; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIR/ WEAPONS MATERIALS DIV
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| Magnesium alloys with rare earth additions have exhibited high strength at room and elevated temperatures and good creep resistance largely due to their age hardenability. This study utilizes solid diffusion couples of pure magnesium and neodymium to observe the formation and growth of intermetallic phases and the interdiffusion behavior of the system. Diffusion anneals were carried out between 400 and 500 C. The resulting microstructures were examined with a scanning ... |
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| Microstructurally Engineered Armor System for Enhanced Survivability through Optimum Energy and Momentum Dissipation |
18 Jun 2012 |
61 pages |
| Authors:
M A Zikry; NORTH CAROLINA STATE UNIV AT RALEIGH
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| This project is focused on the optimization and development of a new class of high strength and lightweight aluminum alloys for armored systems subjected to high rate and severe loading conditions associated with IED events. The current effort is led by North Carolina State University (M.A. Zikry, D. Brenner, NCSU) An integrated experimental and atomistic and microstructural modeling framework has been developed and used to rapidly identify dominant microstructural characteristics ... |
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| Verification and Validation of ICME Methods and Models for Aerospace Applications |
11 Jun 2012 |
17 pages |
| Authors:
Bradford Cowles; Dan Backman; Rollie Dutton; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
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| Integrated Computational Materials Engineering (ICME) model verification and validation (V&V) is difficult because materials processing, microstructural evolution, and property development contain a rich mix of length and time scales with an equally complex set of interacting phenomena and mechanisms. Beyond these difficulties, engineers who adapt these models rarely generate independent validation data sets to confirm model adequacy, quantify uncertainty, and identify potential error sources. Even when a validation data set ... |
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| Microstructurally Engineered Armor System for Enhanced Survivability through Optimum Energy and Momentum Dissipation |
02 Jun 2012 |
55 pages |
| Authors:
M A Zikry; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| This project is focused on the optimization and development of a new class of high strength and lightweight aluminum alloys for armored systems subjected to high rate and severe loading conditions associated with IED events. The current effort is led by North Carolina State University (M.A. Zikry, D. Brenner, NCSU) An integrated experimental and atomistic and microstructural modeling framework has been developed and used to rapidly identify dominant microstructural characteristics ... |
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| Carbon Fiber and Tungsten Disulfide Nanoscale Architectures for Armor Applications |
Jun 2012 |
121 pages |
| Authors:
Michael J Moberg; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The objective of this research was to generate shock-resistant materials based on inorganic fullerene type tungsten disulfide (IF-WS2) and carbon nanocomposite structures for personal protection armor systems. The aim was to develop a new generation of composites that combine the known energy absorbing properties of carbon nanofibers, with the shock absorbing properties reported for IF-WS2 structures. Various methods were explored to generate the desired WS2-carbon fiber composite. Experimentation revealed that ... |
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| Effects of Processing and Powder Size on Microstructure and Reactivity in Arrested Reactive Milled Al + Ni |
May 2012 |
19 pages |
| Authors:
Eric B Herbold; Jennifer L Jordan; N N Thadhani; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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| Ball-milling Al-metal powders can result in self-sustaining high-temperature synthesis in intermetallic-forming systems. Here, Al and Ni powders with similar composition are used to investigate how microstructural differences affect the measured time to reaction (TTR) between powders of different sizes processed under milling conditions specified by statistically designed experiments. Linear statistical models predicting the TTR and the change in temperature (DT) are built from these experimental results. The time required to ... |
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| Microstructure Analysis of Boron Nanotubes |
May 2012 |
13 pages |
| Authors:
Tapan Chatterjee; Stacey Kerwien; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ ENERGETICS WARHEADS AND MANUFACTURING TECHNOLOGY DIRECTORATE
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| Transmission electron microscopy and electron diffraction technique revealed boron nitride nanotube and nanoparticles in thin film boron nitride prepared by CVD method. Electron micrographs show single walled nanotubes containing these nonoparticles. The electron diffraction pattern confirms this boron nitride has a hexagonal crystal structure. |
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| Damage Study in an AA 2024 T3 Panel Subjected to Explosive Loading |
May 2012 |
14 pages |
| Authors:
T Sano; C Fountzoulas; C F Yen; C Chen; M Nansteel; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Aluminum alloys are the prime metallic materials used for light weight industrial applications. Experimental characterization of the damage in AA 2024 T3 alloy subjected to close-in blast loading is one of the critical steps to assess and improve the safety of the passenger and cargo transportation systems. Currently, several aluminum alloys are also considered by the DoD for applications such as armor for vehicles and other protection systems. AA 2024 ... |
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| In-Situ Scanning Electron Microscopy Comparison of Microstructure and Deformation Between WE43-F and WE43-T5 Magnesium Alloys |
May 2012 |
10 pages |
| Authors:
Tomoko San; Jian Yu; Bruce Davis; Richard DeLorme; Kyu Cho; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| In-situ tensile testing in the scanning electron microscope was used to investigate the quasi-static deformation behavior and fracture mechanism of WE43 magnesium alloys. The in-situ tensile experiments were conducted at room temperature at a constant crosshead speed of 0.5 mm/min. One set of samples was a rolled and quenched F temper alloy and the other set was an artificially aged T5 temper alloy. The objective of this research was to ... |
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| Microstructure Analyses of Detonation Diamond Nanoparticles |
May 2012 |
15 pages |
| Authors:
Tapan Chatterjee; Stacey Kerwien; Elias Jelis; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ ENERGETICS WARHEADS AND MANUFACTURING TECHNOLOGY DIRECTORATE
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| Transmission electron microscopy and electron diffraction technique revealed detonation diamond nanoparticles approximately 5.to 6 nm in diameter. The scanning electron microscope pictures showed the octahedral shape and lustrous faces of this bulk nanomaterial. The EDAX analysis from this perfectly well purified powder material showed a single C peak. The electron diffraction and x-ray diffraction patterns confirmed these nanoparticles have octahedral crystal habit and cubic crystal system. |
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| The Effect of Twins on the Mechanical Behavior of Boron Carbide |
May 2012 |
10 pages |
| Authors:
Tomoko Sano; Charles L Randow; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The microstructure and mechanical properties of boron carbide (B4C) samples processed by slip casting were compared with those processed by the conventional hot-pressing technique. Although the quasi-static and dynamic mechanical experiments showed comparable results between the slip-cast and hot-pressed B4C, scanning electron microscopy and electron backscattered diffraction of the B4C samples revealed significant differences in the microstructure. A notable difference was the numerous growth twins in the slip-cast samples. The ... |
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| Dynamic Compressibility, Shear Strength, and Fracture Behavior of Ceramic Microstructures Predicted from Mesoscale Models |
Apr 2012 |
12 pages |
| Authors:
John D Clayton; R B Leavy; Reuben H Kraft; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Fundamental understanding of dynamic behavior of polycrystalline ceramics is advanced through constitutive theory development and computational modeling. At the mesoscale, microstructures of silicon carbide grains (hexagonal crystal structure) or aluminum oxynitride grains (cubic crystal structure) are subjected to compression or shear at high rates with varying confining pressure. Each grain is resolved by numerous three-dimensional finite elements, and behavior of each grain is modeled using nonlinear anisotropic elasticity. Cohesive fracture ... |
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| Microstructural Characteristics of High Rate Plastic Deformation in Elektron (trademark) WE43 Magnesium Alloy |
Apr 2012 |
12 pages |
| Authors:
Joseph Hamilton; Sarah T Brennan; Yongho Sohn; Bruce Davis; Rick DeLorme; Kyu Cho; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| High strain rate deformation of WE43 magnesium alloy was carried out by high velocity impacts, and the characteristics and mechanisms of microstructural damage were examined. Six samples were subjected to a variety of high velocity impact loadings that resulted in both partial and full damage. Optical, scanning and transmission electron microscopy analyses were performed in order to identify regions of shear localization. These regions were used to map, both quantitatively ... |
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| The Role of Rho GTPases in Breast Cancer Migration and Invasion |
Apr 2012 |
7 pages |
| Authors:
Jeffery Smith; SLOAN-KETTERING INST FOR CANCER RESEARCH NEW YORK
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| Rho-family GTPases are the major regulators of the actin and microtubule cytoskeleton. Regulators of the GTPases include GEFs and GAPs, which control activation and deactivation, respectively, of this family of molecular switches. This study explores the role of the GEF Tiam2 in breast cancer cell proliferation and invasion, which was initially discovered using a siRNA screen in MDA-MB-231 breast cancer cells. Protein expression studies are performed using a panel of ... |
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| FDTD Simulation of Novel Polarimetric and Directional Reflectance and Transmittance Measurements from Optical Nano- and Micro-Structured Materials |
22 Mar 2012 |
110 pages |
| Authors:
Spencer R Sellers; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The basic physics of nano-/micro-structured materials must be categorized through measurements and simulation to fully understand their scatter dependence on polarization and angle on incidence before they can be considered for war fighter applications. The off-normal incidence and polarization dependant scatter for a guided-mode resonance filter (GMRF) and a surface plasmonic polariton (SPP) extraordinary transmission filter is measured. The measurements are compared to finite-difference time domain (FDTD) simulations. The GMRF ... |
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| An Image-Based Method for Modeling the Elasto-Plastic Behavior of Polycrystalline Microstructures Based on the Fast Fourier Transform |
16 Mar 2012 |
55 pages |
| Authors:
Bin Wen; Nicholas Zabaras; SIBLEY SCHOOL OF MECHANICAL AND AEROSPACE ENGINEERING ITHACA NY
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| An efficient full-field method of computing the local and homogenized macroscopic responses of elasto-plastic polycrystalline microstructures based on the fast Fourier transform (FFT) algorithm is presented. This approach takes realistic microstructure images as the input and estimates the mechanical response/properties of polycrystal microstructures under periodic boundary conditions without requiring complex discretization. Effective stress-strain response, local mechanical response fields and crystallographic texture of deformed microstructures are examined. Special interest is given ... |
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| Acquisition of Mechanically Assisted Spark Plasma Sintering System for Advanced Research and Education on Functionally Graded Hybrid Materials |
14 Mar 2012 |
25 pages |
| Authors:
DIMITRIS LAGOUDAS; Miladin Radovic; Ibrahim Karaman; TEXAS ENGINEERING EXPERIMENT STATION COLLEGE STATION
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| This is the final progress report of activities at Texas Engineering Experiment Station (TEES)/Texas A&M University (TAMU) on work related to the AFOSR Defense University Research Instrumentation Program (DURIP) Project titled, Acquisition of Mechanically Assisted Spark Plasma Sintering System for Advanced Research and Education on Functionally Graded Hybrid Materials . The effective beginning date of Contract No. FA9550-10-1-0398 was September 15, 2010. The project was aimed at developing facilities for ... |
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| Structure-Property Relationships of Steel Cylindrical Shells |
Mar 2012 |
21 pages |
| Authors:
Ruth G Hidalgo-Hernandez; Paul G Allison; Brett A Williams; Luis A de Bejar; W S Hart; Jason Morson; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| Personnel of the U.S. Army Engineer Research and Development Center (ERDC), Geotechnical and Structures Laboratory (GSL), Engineering Systems and Materials Division (ESMD), Concrete and Materials Branch (CMB), Vicksburg, Mississippi, were asked to examine the mechanical properties and microstructure characteristics of a commercially available steel cylindrical shell in its as-manufactured condition. To examine the mechanical properties, uniaxial tensile experiments were performed on ASTM dog-bone specimens and hoop cross-sectional specimens at displacement ... |
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| Oxidation Behavior of a Refractory NbCrMo0.5Ta0.5TiZr Alloy (Preprint) |
Mar 2012 |
41 pages |
| Authors:
D M Dimiduk; C Woodward; D B Miracle; O N Senkov; S V Senkova; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| Isothermal oxidation behavior of a refractory high entropy NbCrMo0.5Ta0.5TiZr alloy was studied during heating at 1273 K for 100 hours in flowing air. Continuous weight gain occurred during oxidation and the time dependence of the weight gain per unit surface area was described by a parabolic dependence with the time exponent n = 0.6. X-ray diffraction and scanning electron microscopy (SEM) accompanied by energy dispersive X-ray spectroscopy (EDS) showed that ... |
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| An Automated Multi-Modal Serial Sectioning System for Characterization of Grain-Scale Microstructures in Engineering Materials (Preprint) |
Mar 2012 |
11 pages |
| Authors:
Michael Uchic; Michael Groeber; Jonathan Spowart; Megna Shah; Michael Scott; Patrick Callahan; Adam Shiveley; Michael Chapman; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| This paper describes the development of a new serial sectioning system that has been designed to collect microstructural, crystallographic, and chemical information from volumes in excess of 1 cu mm. The system integrates a robotic multi-platen mechanical polishing system with a modern SEM that enables the acquisition of multi-modal data--scanning electron images, EBSD and hyperspectral EDS map--at each section. Selected details of the system construction as well as an initial ... |
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| Characterization of Ultra-high Temperature Ceramics via Transmission Electron Microscopy: In Situ Toughened ZrB2 Composites Through SiC Platelets |
Mar 2012 |
45 pages |
| Authors:
Diletta Sciti; Laura Silvestroni; NATIONAL RESEARCH COUNCIL FAENZA INST OF SCIENCE AND TECHNOLOGY FOR CERAMICS
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| The work described in the following is the first report in this planned 3-year grant, detailing activity over the first 3 months. The project includes the production and microstructural and mechanical characterization of ultra-high temperature ceramics possessing superior fracture toughness, with specific attention on transmission electron microscopy as a fundamental technique to disclose the sintering mechanisms and toughening phenomena occurring in the materials. The materials described in the present report ... |
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| Biological Information Processing in Single Microtubules |
15 Feb 2012 |
8 pages |
| Authors:
Anirban Bandyopadhyay; NATIONAL INST OF MATERIALS AND CHEMICAL RESEARCH TSUKUBA (JAPAN)
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| By measuring fundamental electronic properties of a single brain microtubule, the researchers have found that it learns 500 states by loss-less ferroelectric memory switching. They confirm that a single microtubule is a resonator with large quality factor, simultaneously operating with three distinct resonance bands, in the kHz, MHz and in the GHz frequency domain. It operates in the pico/femto-watt (1mV, 1pA) domain. They have underpinned its wireless communication and information ... |
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| Microstructure Evolution and Composition Control during the Processing of Thin-gage Metallic Foil (Preprint) |
Feb 2012 |
49 pages |
| Authors:
S L Semiatin; D L Ballard; M E Gross; D W Matson; W D Bennett; C D Bonham; A I Ustinov; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| The manufacture of thin-gage superalloy and gamma-titanium-aluminide foil products via near-conventional thermomechanical processing (TMP) and two different vapor-deposition methods was investigated. TMP was based on hot-pack rolling of plate and sheet. Foils of the superalloy LSHR and the near-gamma titanium aluminide Ti-45.5Al-2Cr-2Nb made by this approach exhibited excellent gage control and fine two-phase microstructures. The vapor-phase techniques utilized magnetron sputtering (MS) of a target of the desired product composition or ... |
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| Tuning Porosity of YBa2Cu3O7-delta Vicinal Films by Insertion of Y2BaCuO5 Nanoparticles (Postprint) |
Feb 2012 |
5 pages |
| Authors:
R L Emergo; J Z Wu; T J Haugan; P N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| High critical current density Jc is the most critical specification for high-temperature-superconductor-coated conductors as required by numerous electric power-related applications. This has motivated an intensive research effort on the effects of microstructure on Jc. By growing YBa2Cu3O7-delta YBCO films at a small vicinal angle, we have recently obtained a highly porous structure in these films accompanied with a significantly enhanced Jc. This result raises a challenging question on whether the ... |
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| Controlled Introduction of Flux Pinning Centers in YBa2Cu3O7-x Films during Pulsed-Laser Deposition (Postprint) |
Feb 2012 |
5 pages |
| Authors:
C Varanasi; P N Barnes; J Burke; J Carpenter; T J Haugan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| To introduce controlled random inclusion of nanometer-sized nonsuperconducting particulates in YBa2Cu3O7-x films for flux pinning enhancement, a special pulsed-laser-ablation YBa2Cu3O7-x target with a Y2BaCuO5 sector was made and the films were deposited on LaAlO3 substrates. Initial results showed that the films consist of 10-20 nm-sized precipitates. In a 0.5 micron thick film, a transport critical current density (Jc) 3 MA/sq cm at 77 K in self-field was measured. Magnetization Jc ... |
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| In-Situ Approach to Introduce Flux Pinning in YBCO (Postprint) |
Feb 2012 |
21 pages |
| Authors:
T J Haugan; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Several in-situ methods to introduce ultra-high densities of defects into YBCO to enhance flux pinning are reviewed, including rare-earth or chemical substitution or additions, and nanoparticle additions by various processing methods. The results were compiled using studies published recently or that are publicly available. Superconducting and microstructural properties are compared for different nanoparticle additions including Y211, Y2O3, CeO2, Sm123, MgO, La211, IrZO3, BaZrO3, and mixed (Y,RE)123 compositions. Results are included ... |
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| SM and ND Substiturions in YBCO Films Produced through Metal Organic Deposition (Postprint) |
Feb 2012 |
8 pages |
| Authors:
B C Harrison; J Carpenter; and P N Barnes P Klenk; H Fang; C V Varanasi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| Epitaxial YBa2Cu3O7-x (YBCO) films were produced on non-buffered (100) single crystal LaAlO3 using the metal organic deposition (MOD) method with fluorinated metal acetates. In an effort to enhance the in-field performance of the films, Sm and Nd acetates were fractionally substituted for Y acetate in a series of precursor solutions to incorporate an array of nanoscale flux pinning centers in the post-annealed films. From measurements taken in the non-optimized films ... |
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| Superconducting Properties of (Mx/YBa2Cu3O7-delta y)N Multilayer Films with Variable Layer Thickness x (Postprint) |
Feb 2012 |
11 pages |
| Authors:
T J Haugan; P N Barnes; T A Campbell; N A Pierce; M F Locke; I Brockman; A L Westerfield; J M Evans; R Morgan; P Klenk; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| The superconducting properties of (Mx /YBa2Cu3O7-dy)N multilayer films were studied for varying layer thickness x. Different M phases were examined including green-phase Y2BaCuO5 (211), Y2O3, BaZrO3, CeO2, SmBa2Cu3O7-d (Sm123), brown-phase La2BaCuO5 (La211), and MgO. Multilayer (Mx /YBa2 Cu3O7-dy)N structures were grown by pulsed laser deposition onto SrTiO3 or LaAlO3 single-crystal substrates by alternate ablation of separate YBa2-Cu3O7-d (123) and M targets, at temperatures of 750 deg C to 790 deg ... |
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| Spatial Mechanical Response and Strain Gradient Evolution of Friction Stir Welded Aluminum-2139 |
Feb 2012 |
30 pages |
| Authors:
Brian Justusson; Jessica Medintz; Jian Yu; Constantine Fountzoulas; Chian-Fong Yen; OAK RIDGE INST FOR SCIENCE AND EDUCATION TN
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| With current involvements of the U.S. Military in various peace-keeping and combat operations throughout the world, there is an increase in the deployment of armored military vehicles. Traditional armoring techniques have performed well against particular threats, but, in the recent combat operations, a new threat of improvised explosive devices, the vulnerability of the undercarriage, is being exposed. While thick, steel-structural members have been used in the past, an effort to ... |
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| Oxidation Resistance, Electrical and Thermal Conductivity, and Spectral Emittance of Fully Dense HfB2 and ZrB2 with SiC, TaSi2, and LaB6 Additives |
26 Jan 2012 |
100 pages |
| Authors:
Robert F Speyer; GEORGIA INST OF TECH ATLANTA SCHOOL OF MATERIALS SCIENCE AND MECHANICAL ENGINEERING
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| The oxidation resistances of ZrB2 containing SiC, TaB2, and TaSi2 additions of various concentrations were studied using isothermal thermogravimetry at 1200, 1400, and 1500 deg C. Theoretically-dense ZrB2-SiC two-phase microstructures were isothermally oxidized for 90 min in a thermogravimetric analyzer in flowing air in the range 1500-1900 deg C. The oxidation resistances of theoretically-dense HfB2-SiC test specimens were evaluated via isothermal thermogravimetry at 1600, 1700 and 1800 deg C. The ... |
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| On the Correlation between Morphology of alpha and Its Crystallographic Orientation Relationship with TiB and Beta in Boron Containing Ti-5Al-5Mo-5V-3Cr-0.5Fe Alloy (Preprint) |
Jan 2012 |
16 pages |
| Authors:
P Nandwana; S Nag; R Banerjee; D Hill; H L Fraser; J Tiley; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| While the role of borides on the microstructure of titanium alloys has been discussed in many previous reports, this paper presents the first experimental evidence of (a) the three-dimensional geometry of alpha precipitates confirming their equiaxed morphology, as determined by reconstruction of serially-sectioned scanning electron microscopy images and, (b) the influence of crystallographic orientation relationship between Beta, TiB, and alpha phases on the morphology of alpha precipitates, investigated via detailed ... |
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| Simulating the Mechanical Response of Titanium Alloys Through the Crystal Plasticity Finite Element Analysis of Image-Based Synthetic Microstructures |
Jan 2012 |
103 pages |
| Authors:
Josh Thomas; OHIO STATE UNIV COLUMBUS
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| Micromechanical crystal plasticity finite element simulations of the response of synthetic titanium microstructures are carried out with the goal of quantifying the effect of microstructure on mechanical properties. Two separate materials are studied: (1) an alpha-Beta Ti-6Al-4V material and (2) a highly-textured, rolled lpha Ti-3Al-2.5V sheet material. Performing accurate finite element analyses begins with accurate image-based characterization of the morphological and crystallographic features of the materials at the microstructural scale. ... |
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| Structural Technology Evaluation Analysis Program (STEAP). Task Order 0029: Thermal Stability of Fatigue Life-Enhanced Structures |
Jan 2012 |
108 pages |
| Authors:
Vijay K Vasudevan; Dong Qian; S R Mannava; Gokul Ramakrishnan; Vibhor Chaswal; Amrinder Gill; Zhong Zhou; Sagar Bhamare; CINCINNATI UNIV OH
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| This work combines process parameter variations, finite element (FE) modeling and simulations, characterization, and mechanical testing in a study of the effects of laser shock peening (LSP) on residual stress and microstructure evolution, thermal stability thereof, and fatigue behavior of high-temperature aerospace structural alloys ( Ti-64, Ti-6242, IN718 SPF and IN718 Plus). The aim was to secure a quantified knowledge of the impact of process parameters and high-temperature exposures on ... |
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Reports by Keyword(s)
MICROSTRUCTURE
