| Towards Corrected and Completed Atomic Site Occupancy Analysis of Superalloys Using Atom Probe Tomography Techniques |
17 Aug 2012 |
16 pages |
| Authors:
Simon Ringer; SYDNEY UNIV (AUSTRALIA) ELECTRON MICROSCOPE UNIT
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 | Advanced Atom Probe Tomography (APT) techniques have been developed and applied to the atomic-scale characterization of multi-component nanostructured materials with particular emphasis on the Ni-based superalloys with Platinum Group Metal (PGM) additions. This research has enabled entirely new analysis approaches for solute distribution/segregation analysis, atom probe crystallography, and lattice rectification and has demonstrated potential for converging atomic scale modeling and simulation with atomic resolution microscopy. These findings now sit on ... |
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| Mechanisms of Precipitation of Different Generations of Gamma-Prime Precipitates During Continuous Cooling of a Nickel Base Superalloy (PREPRINT) |
Aug 2012 |
33 pages |
| Authors:
J Tiley; G B Viswanathan; S Nag; R Banerjee; A R Singh; S Chattopadhyay; Y Ren; H L Fraser; UNIVERSITY OF NORTH TEXAS DENTON
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| This paper focuses on developing a mechanistic understanding of the process of multiple nucleation bursts leading to the formation of multiple generations (or populations) with different size distributions, of gamma precipitates during the continuous cooling of a commercially used nickel base superalloy. This mechanistic understanding has been developed based on a number of critical experimental results; direct observation of the multiple nucleation bursts during in situ x-ray diffraction studies in ... |
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| Determination of Gamma-Prime Site Occupancies in Nickel Superalloys Using Atom Probe Tomography and X-Ray Diffraction (Preprint) |
Aug 2012 |
17 pages |
| Authors:
J Tiley; O Senkov; G Viswanathan; S Nag; R Banerjee; J Hwang; UNIVERSITY OF NORTH TEXAS DENTON
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| Rene88 samples were investigated using atom probe tomography and x-ray diffraction using a monochromated synchrotron beam with different energy values to determine the preferred site occupancy of various alloying elements within the ordered gamma/ precipitates. Samples were solutionized and cooled at 24 degree C/min with subsequent aging at 760 degrees C. The synchrotron-based x-ray diffraction results indicate that niobium prefers to reside on the aluminum sublattice site of the gamma ... |
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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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| Effect of Specimen Thickness on the Creep Response of a Ni-Based Single Crystal Superalloy (PREPRINT) |
Aug 2012 |
32 pages |
| Authors:
A Srivastava; S Gopagoni; A Needleman; R Banerjee; V Seetharaman; A Staroselsky; UNIVERSITY OF NORTH TEXAS DENTON
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| Creep tests on Ni-based single crystal superalloy sheet specimens typically show greater creep strain rates and/or reduced strain or time to creep rupture for thinner specimens than predicted by current theories which predict a size independent creep strain rate and creep rupture strain. This size dependent creep response is termed the thickness debit effect. To investigate the mechanism of the thickness debit effect, isothermal, constant nominal stress creep tests were ... |
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| Coarsening Behavior of Gamma Prime Precipitates and Concurrent Transitions in the Interface Width in Ni-14 at%A1-7 at%Cr (Preprint) |
Aug 2012 |
13 pages |
| Authors:
S Meher; T Rojhirunsakool; J Y Ywang; S Nag; J Tiley; R Banerjee; UNIVERSITY OF NORTH TEXAS DENTON DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Coupling atom probe tomography (APT) and transmission electron microscopy (TEM), the temporal evolution of the precipitate morphology and size distribution, and compositional width of gamma/gamma' interface and associated elemental partitioning, has been tracked in a model Ni-14Al-7Cr(at%) alloy, during isothermal annealing at 800 degrees C. During the initial annealing period, accelerated growth of gamma' is accompanied by a gradual decrease in interface width and enhancement of solute partitioning. Further annealing ... |
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| Analysis of Deformation Substructures in a Notched LCF Sample Under Dwell Condition in a Ni-Based Superalloy (PREPRINT) |
Aug 2012 |
9 pages |
| Authors:
G B Viswanathan; Ken Bain; Dan Huber; S Jha; S Sam; J Tiley; Christopher Woodward; H L Fraser; UNIVERSITY OF NORTH TEXAS DENTON
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| Detailed transmission electron microscopy (TEM) studies were conducted on LCF Rene 104 alloy samples tested under dwell conditions to analyze the deformation substructures. Specifically, the focus was to investigate the effect of crack length, in other words, stress intensity factor range deltaK, on the deformation substructures. Thin foils were prepared by focused ion beam method (FIB) from two specific grains along the crack path at varying distances representing varying K ... |
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| The Variability of Fatigue in Notched Bars of IN100 (Preprint) |
Aug 2012 |
8 pages |
| Authors:
Andrew H Rosenberger; Dennis J Buchanan; D'Anthony A Ward; Sushant K Jha; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS DIV
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| IN100 is one of the workhorse nickel-base superalloys of the current fleet of turbine engines owned and operated by the US Air Force. Many of the life-limited locations on fracture critical IN100 components are associated with locations of stress concentrations, e.g. bolt holes, fillets, balance flange scallops, etc. The prior work by Jha, Caton, and others examining the fatigue variability of nickel-base superalloys found a link between the minimum fatigue ... |
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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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| Vacuum Levels Needed to Simulate Internal Fatigue Crack Growth in Titanium Alloys and Nickel-base Superalloys: Thermodynamic Considerations |
01 Mar 2012 |
20 pages |
| Authors:
V Sinha; J M Larsen; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS & MANUFACTURING DIR METALS CERAMICS & NONDESTRUCTIVE EVALUATION DIV/NONDESTRUCTIVE EVALUATION BRANCH
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| Prior studies have examined fatigue growth of surface cracks in vacuum to simulate sub-surface growth in Ti-alloys and Ni-base superalloys. Even with the highest vacuum level attained using state-of-the-artpumps, it is unclear if conditions of internal crack growth are truly simulated. We consider thermodynamics of the oxidation process to help answer this question. This consideration helps explain a previously reported anomalous behavior of longer life in air than in vacuum ... |
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| The Effect of Autoclaving on Torsional Moment of Two Nickel-Titanium Endodontic Files |
Jan 2012 |
8 pages |
| Authors:
J B King; H W Roberts; B E Bergeron; M J Mayerchak; TINKER AFB OK
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| The effect of autoclaving on torsional moment of two nickel titanium endodontic files. Aim To evaluate the effects of repeated autoclaving on torsional strength of two nickel titanium (NiTi) rotary endodontic files: Twisted Files (SybronEndo, Orange, CA, USA) and GT Series X files (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA). Methodology Four groups of 20 GT Series X (size 20, .06 taper) and four groups of 20 Twisted Files (size ... |
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| Dislocation Decorrelation and Relationship to Deformation Microtwins during Creep of a Gamma' Precipitate Strengthened Ni-based Superalloy |
Nov 2011 |
17 pages |
| Authors:
R R Unocic; N Zhou; L Kovarik; C Shen; Y Wang; M J Mills; OAK RIDGE NATIONAL LAB TN MATERIALS SCIENCE AND TECHNOLOGY DIV
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| The evolution of microtwins during high temperature creep deformation in a gamma' strengthened Ni-based superalloy has been investigated through a combination of creep testing, transmission electron microscopy (TEM), theoretical modeling, and computer simulation. Experimentally, microtwin nucleation sources were identified and their evolution was tracked by characterizing the deformation substructure at different stages of creep deformation. Deformation is highly localized around stress concentrators such as carbides, borides and serrated grain boundaries, ... |
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| Insights Gained Through Image Analysis During In-Situ Micromechanical Experiments (Preprint) |
Nov 2011 |
17 pages |
| Authors:
P A Shade; M D Uchic; R Wheeler; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| A custom in-situ testing system has been developed to allow the quantitative study of deformation behavior in microsized specimens with compressive or tensile loading, which allows for ready control of the lateral test frame stiffness. Micromechanical tests have been conducted within the chamber of an SEM, which allows concurrent visualization of plastic flow during the mechanical test. Three distinct experiments are presented for the single crystal nickel-base superalloy Rene N5, ... |
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| High Cycle Fatigue Properties of Haynes 230 (registered trademark) Before and After Exposure to Elevated Temperatures (Preprint) |
Oct 2011 |
8 pages |
| Authors:
R J Morrissey; R John; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| The objective of this work was to investigate the high cycle fatigue properties of a nickel based superalloy, Haynes 230, targeted for use in thermal protection system (TPS) applications. This study includes room temperature testing in longitudinal and transverse directions before and after exposure to elevated temperatures out to 107 cycles using a unique test system specifically developed for thin gage applications. Specimens with thicknesses of 0.127 mm were tested ... |
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| Ab-Initio Molecular Dynamics Simulations of Molten Ni-Based Superalloys (Preprint) |
Oct 2011 |
7 pages |
| Authors:
Christopher Woodward; James Lill; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| Convective instabilities responsible for misoriented grains (freckle defects) in directionally solidified turbine airfoils are produced by variations in liquid-metal density with composition and temperature across the solidification zone. Here, fundamental properties of molten Ni-based alloys, required for modeling these instabilities, are calculated using ab initio molecular dynamics simulations. Previous calculations on elemental, binary and ternary alloys produced liquid-phase molar volumes (V(c,T)) within 0.6-1.8% of available experimental data and demonstrated that ... |
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| Development of Ultra-high Mechanical Damping Structures Based on Nano-scale Properties of Shape Memory Alloys |
27 JUL 2011 |
5 pages |
| Authors:
Jose San Juan; UNIVERSIDAD DEL PAIS VASCO BILBAO (SPAIN) DEPT OF PHYSICS OF CONDENSED MATTER
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| This report results from a contract tasking Universidad del Pais Vasco as follows: The objective of the project is explore micro- and nano-scale pillars fabricated from Cu-Al-Ni shape memory alloys (SMA) to evaluate their potential for ultra-high mechanical damping. This study is spurned by recent discovery by the grantee that micro/nano pillars milled from Cu-Al-Ni SMA exhibit anomalously high mechanical damping compared to other materials. The project consists of two ... |
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| Precipitation of Ordered Phases in Metallic Solid Solutions: A Synergistic Clustering and Ordering Process (Preprint) |
Jul 2011 |
19 pages |
| Authors:
R Banerjee; A Singh; S Nag; G B Viswanathan; Jaimie Tiley; H L Fraser; UNIVERSITY OF NORTH TEXAS DENTON
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| The precipitation mechanism of ordered phases in metallic solid solutions has been a long-standing controversy due to the competing roles of chemical clustering (or phase separation) and chemical ordering. In the present study, this controversy has been resolved through the coupled use of aberration-corrected high-resolution scanning transmission electron microscopy and atom probe tomography. Thus, the experimental results, obtained at atomic resolution, can be interpreted satisfactorily only on the basis of ... |
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| Creep and Fatigue Interaction in the PWA 1484 Single Crystal Nickel-Base Alloy (Preprint) |
Jul 2011 |
|
| Authors:
Christian J Pierce; Andrew H Rosenberger; Anthony N Palazotto; 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 methods for modeling creep behavior of single crystal turbine airfoils are generally well developed, constant load creep does not fully represent the loading conditions present in a jet engine due to cyclic loading caused by the mission profile and throttle movements. As the aerospace industry seeks to become more accurate in physics-based modeling of materials that are used in turbine blades, creep-fatigue interaction must be incorporated into characterization of ... |
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| Developing the Capability to Monitor Small Fatigue Crack Growth Under Elevated Temperature, Ultra-High Vacuum Conditions (Preprint) |
Jul 2011 |
20 pages |
| Authors:
M J Caton; A H Rosenberger; B T Gockel; S K Jha; C J Szczepanski; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| It has been observed that the life limiting fatigue behavior in numerous superalloys is dominated by small crack growth behavior. While environmental effects on crack growth behavior of Ni-base superalloys are well documented within the literature, the published research is largely limited to long crack behavior due to the difficulty of measuring small cracks in a vacuum chamber. A testing capability for optical measurement of small cracks under ultra-high vacuum ... |
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| Microstructure and Texture Evolution During Hot Pack Rolling of Nickel-Base Superalloys to Thin Sheet and Foil (Preprint) |
MAR 2011 |
34 pages |
| Authors:
D. L. Ballard; D. S. Weaver; S. L. Semiatin; A. L. Pilchak; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIR METALS CERAMICS AND NONDESTRUCTIVE EVALUATION DIV/METALS BRANCH
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| Microstructure evolution during hot pack rolling of nickel-base superalloys to -l-mm thick sheet and -200-micron-thick foil was investigated with electron backscatter diffraction. The microstructure was observed at increasing levels of strain which revealed the progressive formation of an unrecrystallized, banded microstructure at sheet gage. The bands contained large orientation gradients, sometimes spanning multiple texture components that are considered to be stable with respect to the imposed plane-strain compression. Upon reaching ... |
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| Representation and Reconstruction of Three-dimensional Microstructures in Ni-based Superalloys |
20 DEC 2010 |
32 pages |
| Authors:
Marc de Graef; CARNEGIE-MELLON UNIV PITTSBURGH PA
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| We have applied the theory of 3-D moment invariants to a variety of shapes, including experimental serial sectioning data sets and synthetically generated microstructures. The method is easy to use, and allows for a quantitative description of shapes. Further applications of this approach are currently being considered, including extension to higher order moment invariants. |
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| The Effect of Hardness on Eddy Current Residual Stress Profiling in Shot-Peened Nickel Alloys |
22 Jun 2010 |
12 pages |
| Authors:
Bassam A Abu-Nabah; Waled T Hassan; Daniel Ryan; Mark P Blodgett; Peter B Nagy; GENERAL ELECTRIC AVIATION CINCINNATI OH
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| Recent research results indicate that eddy current conductivity measurements can be exploited for nondestructive evaluation of subsurface residual stresses in surfacetreated nickel-base superalloy components. According to this approach, first the depth-dependent electric conductivity profile is calculated from the measured frequency-dependent apparent eddy current conductivity spectrum. Then, the residual stress depth profile is calculated from the conductivity profile based on the piezoresistivity coefficient of the material, which is determined separately from ... |
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| Technique for Automated Extraction of Symmetric Microstructural Features: Application to Dendritic Cores in Single Crystal Ni-Based Superalloys |
14 JUN 2010 |
21 pages |
| Authors:
M. A. Tschopp; M. A. Groeber; J. P. Simmons; A. H. Rosenberger; C. Woodward; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Serial sectioning methods continue to produce a wealth of image data for quantifying the three-dimensional nature of material microstructures. In this work, we discuss a computational methodology for automated detection and 3D characterization of dendrite cores from images taken from slices of a production turbine blade made of a heat-treated single crystal Ni-based superalloy. The dendrite core locations are detected using an automated segmentation technique that incorporates information over multiple ... |
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| Recursive Dispersion Relations in One-Dimensional Periodic Elastic Media |
Feb-2009 |
30 pages |
| Authors:
Ani P Velo; George A Gazonas; Erwin Bruder; Nancy Rodriquez; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A frequency bandgap is a range of wave frequencies that are prohibited from passing through a medium. The dispersion relation, which links the frequency to the wave number, enables us to illustrate the bandgaps. In [E. H. Lee, A survey of variational methods for elastic wave propagation analysis in composites with periodic structures, in Dynamics of Composite Materials, E. H. Lee, ed., ASME, New York, 1972, pp. 122-138] and [E. ... |
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| A Coupled Creep Plasticity Model for Residual Stress Relaxation of a Shot Peened Nickel-Base Superalloy (Postprint) |
Sep-2008 |
12 pages |
| Authors:
Reji John; Dennis J Buchanan; Robert A Brockman; Andrew H Rosenberger; DAYTON UNIV OH RESEARCH INST
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| Shot peening is a commonly used surface treatment process that imparts compressive residual stresses into the surface of metal components. Compressive residual stresses retard initiation and growth of fatigue cracks. During the component loading history, loading, or during elevated temperature static loading, such as thermal exposure and creep. In these instances, taking full credit for compressive residual stresses would result in a methodical approach for characterizing and modeling residual stress ... |
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| The Mean vs Life-Limiting Fatigue Response of a Ni-Base Superalloy, Part 2: Life Prediction Methodology (Preprint) |
Sep-2008 |
22 pages |
| Authors:
S K Jha; J M Larsen; M J Caton; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| In Part 1, we showed that the mean fatigue behavior of IN100 separates from the life-limiting response as stress level is decreased. This separation of lifetimes was suggested to be related to the development of heterogeneity levels of local deformation that produce sequential occurrence of short-lifetime and the mean-lifetime dominating mechanisms. In the current paper, we show that the distribution in the life-limiting mechanism is controlled by small-crack growth from ... |
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| Energy Barriers and Hysteresis in Martensitic Phase Transformations |
Aug-2008 |
40 pages |
| Authors:
Zhiyong Zhang; Richard D James; Stefan Muller; MINNESOTA UNIV MINNEAPOLIS DEPT OF AEROSPACE ENGINEERING AND MECHANICS
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| We report results from a systematic program of changing composition of alloys in the system TiNiX, X= Cu, Pt, Pd, Au, to pursue certain special lattice parameters that have been identified previously with low hysteresis. We achieve lambda2 = 1, where lambda2 is the middle eigenvalue of the transformation strain matrix, for alloys with X = Pt, Pd, Au. In all cases there is a sharp drop of the graph ... |
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| Damping MEMS Devices in Harsh Environments Using Active Thin Films |
17-Jun-2008 |
26 pages |
| Authors:
Greg P Carman; Catherine A Kerrigan; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| We report on fabrication and damping measurement of NiTi and Terfenol-D thin films. A model for prediction of the damping properties (tan delta) of a laminate using the material properties of the layers was developed. Damping properties in Nitinol thin film due only to residual stresses was measured to be as high as tan delta = 0.17 for large strain (0.9%). At lower strain levels a Nitinol/Silicon laminate was tested ... |
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| Yield Strengths of Biaxially Textured Metallic Substrates (Ni and Its Alloys) Determined Using a Simplified Test Method (Postprint) |
14 Sep 2007 |
7 pages |
| Authors:
Chakrapani Varanasi; Leon Chuck; Lyle Brunke; Jack Burke; Andrew D Chaney; Paul N Barnes; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIR/POWER DIV/MECHANICAL ENERGY CONVERSION BRANCH
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| A simple testing method is used to compare the yield strengths (YS) of biaxially textured metallic substrates (Ni and its alloys) presently under development for YBa2Cu3O7-x coated conductors. This method is based on a retired ASTM D3379 tensile test standard method that was originally recommended for single filament materials. Several common textured substrates, such as Ni, Ni-3at.%W, and Ni-5at.%W, procured from different manufacturers, were tested using this method, and the ... |
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| Nano-SMA Fiber Composites Development and Applications |
27 JUL 2007 |
7 pages |
| Authors:
H. Kato; H. Tamagawa; HOKKAIDO UNIV SAPPORO (JAPAN)
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| We design a set of self-strengthening AMCs with shape memory nanofibers with the aim of inducing compressive stress at different use temperatures; (i) high temperature for leading edge structure panels or those near engine and (ii) low temperatures for composite face sheets of AF cryogenic tanks. To this end, two types of SM nanofibers will be used, shape memory alloy (SMA) and shape memory polymer (SMP). SMA exhibit phase change ... |
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| Growth and Characterization of Carbon Nanotubes on Constantan (Cu-Ni-Mn Alloy) Metallic Substrates Without Adding Additional Catalysts |
Jul-2007 |
6 pages |
| Authors:
J Bulmer; J Baca; K Yost; P Barnes; C V Varanasi; L Brunke; J Burke; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| In this study, metallic constantan (Cu55-Ni44-Mn1 wt %) alloy substrates were investigated as an alternate choice of substrates to grow carbon nanotubes (CNTs). No additional catalysts were used other than the as-rolled and annealed substrates to process CNTs on them. High density CNT growth was observed to take place on these substrates when suitable conditions were used in a thermal chemical vapor deposition (CVD) furnace with C2H2 as the carbon ... |
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| The Effect of Microstructure on Fretting Fatigue Behavior of Nickel Alloy IN-100 |
MAR 2007 |
130 pages |
| Authors:
Erik C. Saladin; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This thesis studied the effect of microstructure on the fretting fatigue behavior of IN-100. First, fretting and plain fatigue S-N curves were determined over a large range of applied stress at an identical R-ratio and for fretting tests, done with a constant contact load. It was found that fretting fatigue reduces the cycles to failure compared to plain fatigue. The half contact width was found for the specimens, the crack ... |
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| Friction Stir Processing Parameters and Property Distributions in Cast Nickel Aluminum Bronze |
DEC 2006 |
67 pages |
| Authors:
Brian P. Rosemark; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING
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| Cast nickel-aluminum bronze (NAB) alloy is specified for many marine applications, including ship propellers, due to its excellent corrosion-resistance combined with acceptable mechanical properties. Friction stir processing (FSP) can be used to improve the alloy's mechanical properties by localized microstructure modification in the cast material. FSP converts an as-cast microstructure to a wrought condition in the absence of macroscopic shape change, closes porosity, and provides a means to surface harden ... |
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| Grain Boundary Curvature in a Model Ni-Based Superalloy (Preprint) |
JUL 2006 |
23 pages |
| Authors:
Kai Song; Mark Aindow; CONNECTICUT UNIV STORRS INST OF MATERIALS SCIENCE
|
| The local grain boundary curvature in a model Ni-based superalloy was measured experimentally using Dehoff's tangent count method. The results show that, in materials containing significant amounts of second-phase particles, the curvature parameter kappa, which relates the mean local curvature to the grain size, can adopt far lower values than have been reported previously. It is also shown that the value of kappa, is not a constant, as is usually ... |
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| Corner Crack Propagation in the Presence of Residual Stresses (Preprint) |
MAY 2006 |
12 pages |
| Authors:
A. L. Hutson; M. Huelsman; D. Buchanan; R. John; S. Haering; DAYTON UNIV OH RESEARCH INST
|
| BA technology development program known as Engine Rotor Life Extension (ERLE) has been initiated by the United States Air Force. One of the key technologies being assessed under the ERLE program is the analysis of 3D crack propagation at critical locations in turbine engine components. These critical locations are typically shot peened requiring the ability to predict 3D crack propagation at stress concentration sites in the presence of residual stresses. ... |
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| Fundamental Studies of Strengthening Mechanisms in Metals Using Dislocation Dynamics |
26 MAR 2006 |
14 pages |
| Authors:
Tariq Khraishi; Yu-Lin Shen; NEW MEXICO UNIV ALBUQUERQUE DEPT OF MECHANICAL ENGINEERING
|
| A distributed dislocation method has been developed to quantify the elastic fields of inclusion eigenstrain problems in 2D and 3D (Lerma et al. 2003). The inclusions can be of any shape or size and the eigertstrains can be arbitrarily assigned, i.e. constant or non-constant within the inclusion. The method works well for material or field points inside or outside the inclusion domain, and is straightforward to apply. The method is ... |
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| A Life Prediction Approach for Reliable Improvement in Utilization Potential of P/M Nickel-Based Superalloy Components (Preprint) |
FEB 2006 |
14 pages |
| Authors:
Sushant K. Jha; Michael J. Caton; III. Porter William J.; Kezhong Li; James M. Larsen; Andrew H. Rosenberger; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| The fatigue variability behavior of a powder processed nickel-based superalloy, IN-100 was studied and is discussed with respect to the design life prediction. We found that the stress level, and other loading variables produce distinct effects on the mean behavior and the life-limiting (or the worst-case) behavior. This was because; while the mean was dominated by the conventionally expected fatigue response to these variables the life-limiting behavior was controlled by ... |
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| Development of a Swashplateless Rotor Using Magnetic Shape Memory Alloys |
31 MAR 2005 |
18 pages |
| Authors:
Ronald N. Couch; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
|
| A quasi-static model for NiMnGa magnetic shape memory alloy (MSMA) is formulated in parallel to the Brinson and Tanaka thermal SMA constitutive models. Since the shape memory effect (SME) and pseudoelasticity exist in both NiTi and NiMnGa, constitutive models for SMAs can serve as a basis for MSMA behavioral modeling. The quasi-static model for NiMnGa was characterized by nine material parameters identified by conducting a series of uniaxial compression tests ... |
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| Biaxial Fatigue Behavior of Niti Shape Memory Alloy |
MAR 2005 |
101 pages |
| Authors:
Daniel M. Jensen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Nitinol is a shape memory alloy (SMA) capable of martensite-to- austenite phase transformations enabling shape-memory behavior. Shape-memory properties make Nitinol a strong candidate material for use in aircraft applications such as actuators. Structural integrity and reliability of torque tube actuators must be assured before this material can be used in flight- critical components. Thorough understanding of the fatigue response of the material is essential for a structurally-sound SMA actuator design. ... |
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| Localization of Deformation in Heterogeneous Solids Deformed at High Strain Rates |
31 JAN 2005 |
111 pages |
| Authors:
B. M. Love; R. C. Batra; VIRGINIA POLYTECHNIC INST BLACKSBURG
|
| Plane strain transient finite thermomechanical deformations of heat- conducting particulate composites comprised of circular tungsten particulates in nickel-iron matrix are analyzed using the finite element method to delineate the initiation and propagation of brittle/ductile failures by the nodal release technique. Each constituent and composites are modeled as strain-hardening, strain-rate-hardening and thermally-softening microporous materials. Values of material parameters of composites are derived by analyzing deformations of a representative volume element whose ... |
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| Magnetic Studies of Substrate and Superconductive Materials for Development of Advanced Coated Conductors |
19 NOV 2004 |
5 pages |
| Authors:
James R. Thompson; TENNESSEE UNIV KNOXVILLE DEPT OF PHYSICS
|
| A scientific study has been concluded on the energy loss in advanced coated superconducting wires and tapes that arise from the presence of ferromagnetic substrate materials. Since Ni-W alloys are being used presently as substrates in prototype commercial conductors, a thorough investigation was conducted on the magnetic and loss properties of a series of Ni(sub 1-x)Wx biaxially textured alloys, for the entire range of ferromagnetism, x = 0-9 at% W. ... |
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| NiAl Bond Coats Made by a Directed Vapor Deposition Approach |
OCT 2004 |
11 pages |
| Authors:
Z.. Yu; D. D. Hass; H. N. Wadley; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Intermetallic, nickel aluminide alloys are widely used as bond coat materials in thermal barrier coating systems applied to nickel base super alloy components. They are usually synthesized by a solid-state reaction diffusion heat treatment following the chemical vapor deposition of aluminum on the nickel rich substrate. Here, an electron beam directed vapor deposition (EB-DVD) technique is used to simultaneously evaporate nickel and aluminum and then reactively deposit NiAl bond coats ... |
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| Computational Design of Advanced Aeroturbine Materials: Noburnium Cyberalloy |
AUG 2004 |
38 pages |
| Authors:
Gregory B. Olson; Arthur J. Freeman; Mark D. Asta; Gautam Ghosh; John H. Perepezko; Mark E. Eberhart; C. Woodward; NORTHWESTERN UNIV EVANSTON IL
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| Under the AFOSR-MEANS initiative, an optimal combination of electronic-level first-principles calculations and efficient experimentation addresses the accelerated design and development of a new class of Nb-based aeroturbine superalloys. |
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| Elevated Temperature Fretting Facility |
JUL 2004 |
5 pages |
| Authors:
Richard W. Neu; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
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| The primary equipment purchased is a Phoenix Tribology Ltd. DN55 High Temperature Sliding and Fretting Machine. The machine was designed from the ground up specifically for high temperature (up to 8OOoC) fretting experiments. The system has lower mass actuator system which is ideal for fretting and reciprocal sliding experiments to enable cycling at higher frequencies (up to 500 Hz) while minimizing dynamic effects. The system can also perform reciprocating sliding ... |
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| Advanced High Cycle Fatigue Life Assurance Methodologies |
JUL 2004 |
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| Authors:
J. Gallagher; T. Nicholas; A. Gunderson; J. Ruschau; P. Miedlar; DAYTON UNIV OH RESEARCH INST
|
 | This program was a follow-on effort to a program on improved High Cycle Fatigue (HCF) Life Prediction, the results of which are documented in the final report on that PRDA program. This program continued work on addressing key issues associated with developing, verifying, & implementing a material damage tolerant design methodology capable of predicting HCF limits & material thresholds for Ti-6A1-4V. The methodology development was extended to another titanium alloy, ... |
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| Advanced High Cycle Fatigue (HCF) Life Assurance Methodologies |
JUL 2004 |
1161 pages |
| Authors:
J. Gallagher; T. Nicholas; A. Gunderson; J. Ruschau; P. Miedlar; A. Hutson; g. hardy; D. Walls; C. Annis; R. deLaneuville; DAYTON UNIV OH RESEARCH INST
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| This program was a follow-on effort to a program on Improved High Cycle Fatigue (HCF) Life Prediction, USAF Contract F33615-96-C-5269, the results of which are documented in the final report on that PRDA program 1. This program continued work on addressing key issues associated with developing, verifying, & implementing a material damage tolerant design methodology capable of predicting HCF limits & material thresholds for Ti-6Al-4V. The methodology development was extended ... |
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| The Isothermal Deformation of Nickel Aluminum Bronze in Relation to the Friction Stir Processing |
JUN 2004 |
71 pages |
| Authors:
Frank A. Pierce; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The extreme strain, strain rate and temperature gradients during Friction Stir Processing (FSP) render measurement of key parameters in the stir zone infeasible with common methods. The objective of this research was to separate the effects that temperature and deformation in an experimental study of the microstructure and mechanical properties of Ni-AL bronze (NAB). This was accomplished by subjecting as-cast NAB material to several isothermal annealing and quenching treatments as ... |
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| Life Prediction Methodologies for Aerospace Materials |
JUN 2004 |
109 pages |
| Authors:
N. E. Ashbaugh; R. A. Brockman; D. J. Buchanan; G. A. Hartman; A. L. Huston; K. Li; W. J. Porter; DAYTON UNIV OH RESEARCH INST
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| Superalloys IN-100, Ren 88DT, Waspaloy, and titanium alloys were investigated. For life-limiting responses in superalloys, highly localized stress-deformation behaviors associated with both typical and unusual defects were developed. Characterizing the relaxation of residual stresses in a component due to temperature, exposure time, and mechanical loading is essential to development of a physics-based life prediction model. Current life management concepts based on damage tolerance have not incorporated the effects of surface ... |
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| M1 Abrams Seal Ring |
26 APR 2004 |
2 pages |
| Authors:
NATIONAL CENTER FOR DEFENSE MANUFACTURING AND MACHINING LATROBE PA
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| The U.S. Army's Anniston Depot in Anniston, Alabama, is designated the Center of Technical Excellence for the M1 Abrams Tank division of the Tank-Auto and Armaments Command (TAACOM). The Depot was commissioned to reduce the manufacturing time of a housing seal for the M1 Abrams engine. The 3.650-inch-diameter, 0.500-inch-wide seal, made of wrought A-286 nickel-iron super alloy, is difficult to clamp securely during machining, making it a challenge to maintain ... |
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| Dynamic Recrystallization of Low Stacking Fault Energy Metals |
18 MAR 2004 |
18 pages |
| Authors:
Frank Montheillet; Jean-Philippe Thomas; ECOLE NATIONALE SUPERIEURE DES MINES SAINT-ETIENNE (FRANCE)
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| Viewgraphs of presentation on the dynamic recrystallization of low stacking fault energy metals. |
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Reports by Keyword(s)
NICKEL ALLOYS
