| Multi-Scale Simulation of Interfacial Phenomena and Nano-Particle Placement in Polymer Matrix Composites |
Aug 2012 |
32 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | Outline: Simulation approach, Generating Realistic Structures, Structural Ubiquities, Property Prediction and Analysis of governing Principles and Summary and Outlook. |
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| Solar and Thermal Energy Harvesting Textile Composites for Aerospace Applications |
Jun 2012 |
10 pages |
| Authors:
Max Shtein; Kevin Pipe; Peter Peumans; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The overall goal of the project was to design and demonstrate fiber-based energy harvesting devices that can convert light and heat to electricity, and be integrated into air vehicle structures. Specifically, in Year 1, we set out to design and demonstrate photovoltaic and thermoelectric devices on polymer fibers. In Years 2 and 3, we sought to improve the performance of individual energy converting fibers, as well as to develop models ... |
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| Superoleophobic yet Superhydrophilic surfaces for Continuous Liquid-Liquid Separation |
08 Dec 2011 |
21 pages |
| Authors:
Anish Tuteja; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| There is a critical need to develop new energy-efficient solutions for the separation of oil-water mixtures, including those stabilized by surfactants. Traditional membrane-based separation technologies for oil-water mixtures are energy-intensive and further limited, either by fouling or the inability of a single membrane to separate all types of oil-water mixtures. The ideal membrane to effect gravity-driven separation of oil-water mixtures is expected to be both hydrophilic and oleophobic, in air ... |
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| Gamma Prime Morphology and Creep Properties of Nickel Based Superalloys With Platinum Group Metal Additions (Preprint) |
Apr 2008 |
12 pages |
| Authors:
J S Sluytman; A Suzuki; A Bolcavage; R C Helmink; D L Ballard; T M Pollock; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The microstructure and creep properties of platinum group metal (PGM) modified nickel based superalloys have been investigated. Alloys containing Pt and/or Ir along with variations in Cr, Ta, Re, Ru, and W exhibited relatively high solidus and liquidus temperatures. Differential thermal analysis (DTA) showed a strong dependence of the gamma' solvus on the level of Ta. The morphology of the gamma' precipitates was influenced by the presence of Cr, Ta, ... |
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| MEANS 2: Microstructure- and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems |
22 Feb 2008 |
12 pages |
| Authors:
Tresa M Pollock; Michael J Mills; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This effort has focused on verification and refinement of the mechanism transitions at intermediate temperatures in the disk alloy Rene 104, with the observation of microtwinning, continuous faulting and dislocation by-pass at successively higher temperatures above 650 degrees C. Evidence for the twin initiation process has also been obtained via TEM studies of specimens interrupted after small strain levels. A model for the novel microtwinning regime. Modeling at the ab ... |
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| Seed Effort Toward "Multiscale Theoretical and Experimental Investigation of the Role of Structural Features on Damage Tolerance and Creep" |
NOV 2007 |
31 pages |
| Authors:
Amit Ghosh; Rick Lee; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This report summarizes research ideas and some results in relation to effort conducted toward understanding the role of grain boundaries and grain boundary defects on the mechanical properties of metals, and with evolving interest in testing and learning the behavior of small specimens. It has been shown that by considering grain boundaries having different properties from grains, strengthening of metals as affected by grain size can be predicted. The analysis ... |
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| Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys using Ultrasonic Fatigue |
23 Jun 2007 |
50 pages |
| Authors:
J W Jones; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Ultrasonic fatigue (20kHz) has been used to investigate the role of microstructural variability on fatigue life variability for very long fatigue lives, between 10(to the 7th power) and 10(to the 9th power) cycles, in structural aerospace materials. This AFOSR program has been augmented by support from DARPA (Dr. Leo Christodoulou) and a summary of the results from the combined support is described in this report. Four distinctly different structural alloys ... |
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| Combinatorial Production and Processing of Oxide Nanopowders for Transparent, Ceramic Lasers |
JUN 2007 |
86 pages |
| Authors:
Richard M. Laine; Stephen C. Rand; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Since the discovery of transparent polycrystalline alumina by Coble in 1962, transparent and translucent alumina and yttria based ceramics have achieved a significant presence in our everyday lives because of their utility in sodium (and metal halide) vapor lamp envelopes used for example in street lights (automotive lighting). More recently, transparent ceramic scintillators have replaced photographic film in most medical X-ray imaging equipment. Although known for 30 years, transparent ceramic ... |
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| Molecular Modeling of Interfacial Behaviors of Nanomaterials |
MAY 2007 |
14 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| During this project period we focused predominantly on explicit-atom MD simulations and first principles DFT calculations. This involved the force field parameterization for new molecules, i.e., cyclopentene, and the exploration of various DFT codes to identify the one most suitable for our purpose. We conducted several proof of concept studies, concentrating on the structural developments in the immediate vicinity of the surface with which the polymer comes into contact. These ... |
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| Multiscale Modeling for the Design of Autonomic Healing Structural Composite Materials (MEANS) |
25 JUN 2006 |
14 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| We developed a suite of molecular-scale simulation tools, which includes all-atom MD simulations and coarse-graining procedures to interface with CVFE calculations at the continuum level. Polymerization reaction mechanisms and rates are identified in all-atom simulations. A first coarse-graining procedure consists of eliminating atoms that are unimportant for the mechanical properties of the structure. In a second coarse-graining procedure representation of monomers is simplified to spherically symmetric particles. This allows one ... |
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| Local Strain Development and Property Variability in B2 Intermetallics |
19 SEP 2005 |
25 pages |
| Authors:
Tresa M. Pollock; Marc de Graef; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The overall objective of this research program was to develop a quantitative understanding of the relationship of straining processes at the scale of microstructure to macroscopic mechanical properties of structural materials. To accomplish this, experimental high-resolution displacement mapping techniques for analysis of strains at the micron scale were developed and validated. Strain accumulation and its relationship to microstructural features in several variants of the B2 intermetallic RuAl were investigated. Significant ... |
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| Multiscale Modeling for the Design of Autonomic Healing Structural Composite Materials |
31 AUG 2004 |
10 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This MEANS initiative research project consists of a collaborative effort between students, postdocs, and faculty at the University of Illinois and at the University of Michigan. The work involves the integration of length and time scale spanning computational methods of investigation into a suite of design tool for materials optimization. Concurrent experimental measurements serve to motivate and validate the simulation approaches. Specifically, the challenges posed by the design of autonomously ... |
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| Characterization of the Structure of a Novel Refractory Alloy Glass - Ni60Nb37Sn3 |
Jan 2002 |
7 pages |
| Authors:
Michelle L Tokarz; Matt Daniels; John C Bilello; Zofia Rek; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Bulk forms of Refractory Alloy Glasses (RAGs) of the composition Ni60Nb37Sn3 have recently been synthesized as part of a larger project for potential use in structural applications. Modeling efforts of such metallic glasses have traditionally involved the use of hard sphere models without regard to potential electron density fluctuations of individual components. X-ray characterization of these materials (in both reflection and transmission modes) provided scattering data necessary for subsequent radial ... |
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| Fabrication of High-Performance Coatings Systems via a Novel In-Situ/Ex- Situ Characterization Technique |
31 JUL 2001 |
21 pages |
| Authors:
John C. Bilello; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| This report will briefly outline some of the key findings made during the course of this project and some new work on the phase structure changes concomitant with the delamination behavior of Ta metallizations. Detailed accountants of prior work have been in included in previous "Interim Reports" of this Grant and in the many technical papers that have resulted from the support of this work. A complete list of these ... |
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| Molecular and Microstructure Scale Models of CVD Diamond Growth |
20 MAR 2000 |
9 pages |
| Authors:
David J. Srolovitz; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This project developed atomistic and microstructural models for the growth of polycrystalline thin films. The atomistic simulations were based upon the kinetic Monte Carlo method and employed experimental and first-principles data for different surface reactions. The models predict the atomic structure of the film, the surface structure, point defect incorporation and the growth rate of different surfaces. The microstructural models employ the atomistic simulation predictions of growth rate for different ... |
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| Ultrahigh Strength-Tough Surface Coatings Via Controlled Nanostructures |
15 MAR 1999 |
20 pages |
| Authors:
John C. Bilello; Steven M. Yalisove; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| In the final phase of this contract a new method for direct determination of strains in amorphous thin films using Grazing Incidence X-ray Scattering (GIXS) data of is described. Results for the residual stress distributions for sputter deposited B4C and SiC are compared to results obtained from more traditional x-ray methods such as Double Crystal X-ray Topography (DCDT). This new approach directly measures quantities intrinsic to the film independent of ... |
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| DURIP 98-99: Molecular Beam Epitaxial Growth and In Situ Characterization of Phase Separated Optoelectronic Semiconductors |
28 FEB 1999 |
10 pages |
| Authors:
Mirecki Millunchick; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This proposal requested funding to procure a Molecular Beam Epitaxy (MBE) chamber with extensive in situ diagnostic capabilities to study phase separation of III-V semiconductor alloys during epitaxial growth. An EPI930 Molecular Beam Epitaxy system was purchased from EPIMBE Products Group and installed in September of 1998, and is fully operational. This piece of equipment has facilitated several new research programs in the area of morphological and compositional evolution in ... |
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| Non-Oxide Structural Ceramics - Alloy Design for Improved Sinterability and Mechanical Performance |
12 MAY 1998 |
8 pages |
| Authors:
I. W. Chen; Tseng Ying Tien; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Research on non-oxide structure ceramics including silicon nitride, silicon carbide and titanium diboride has been conducted Multiphase silicon nitride composites with melilite and other high nitrogen content grain boundary phases have been prepared. These composites can be sintered to high density and they show improved oxidation resistance. Mechanical properties have been evaluated and found to compare favorably with other silicon nitride materials. Phase relations have also been delineated for various ... |
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| DURIP Proposal for An Ion-Assisted Sputtering Deposition System for Nano-Modulated Oxide Coatings |
21 JAN 1998 |
3 pages |
| Authors:
I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Major requisitions include a four-target RF sputtering system from Denton Vacuum Industry and a scanning probe microscope system from AutoProbe Inc. Using these instruments, oxide thin films of various compositions and heterostructures have been prepared to investigate the phenomenon of fatigue. It was found that the rate of degradation is sensitive to the type of charge carriers. Electrons accelerate fatigue while holes do not. It was also found that fatigue ... |
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| Moisture Effect in Composites and Structural Adhesives: A Fundamental Study of Underlying Mechanisms |
20 NOV 97 |
10 pages |
| Authors:
Albert F. Yee; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| High temperature resistant epoxy resins are typically very polar materials and are capable of absorbing considerable quantities of water, typically 1 to 7% by weight. In addition to being very polar, the resulting glassy structures can also be extremely heterogeneous in terms of electron density as a result of the cure process being limited by diffusion. The focus of this work is to quantify this heterogeneous nature in terms of ... |
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| Free Form Fabrication of Ceramics by Stereolithography |
25 AUG 97 |
41 pages |
| Authors:
John W. Halloran; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| During this grant we showed that stereolithography can directly fabricate ceramic green bodies from ultraviolet (UV) curable solutions which contain dispersed ceramic powders. We demonstrated SLA of silica, a model refractory for metal casting molds, and SLA of alumina, which is promising for structural ceramics. Viscosity control for these highly concentrated suspensions and cure depth behavior were the main issues for fabricating a ceramic using stereolithography techniques. These ceramic SLA ... |
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| Tough Ceramics from Fibrous Monoliths |
25 AUG 97 |
66 pages |
| Authors:
John W. Halloran; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| During this 1991-1993 grant, the University of Michigan developed "fibrous monolithic ceramics", a new class of monolithic ceramics with properties comparable to ceramic fiber reinforced ceramic matrix composites CMC's. They consist of a 250-micron "cells" of a strong polycrystalline ceramic, such as silicon carbide or silicon nitride, separated by "cell boundaries" from materials, such as boron nitride, which promote crack deflection and delamination. These materials show graceful failure in flexure, ... |
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| Stereolithography Apparatus for Free Form Fabrication of Ceramics |
25 AUG 97 |
24 pages |
| Authors:
John W. Halloran; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| During this grant we installed a 3D Systems SLA 250/40 stereolithography apparatus, and used it to directly fabricate ceramic green bodies from ultraviolet (UV) curable solutions which contain dispersed ceramic powders. We emphasized SLA of alumina as a structural ceramic and for investment casting cores. Viscosity was reduced with improved dispersion. The quality of the prototypes was improved by determination of appropriate build styles, and by optimization of photoinitiators and ... |
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| Growth and Characterization of Refractory Metal Multilayers: Potential Ultra-High Strength-High Temp Surface Coatings |
31 DEC 1996 |
13 pages |
| Authors:
John C. Bilello; Steven M. Yalisove; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Two important fundamental results have been achieved which have broad application to the whole field of thin films and multilayer coatings. 1) Residual Stress: The first is that residual stress plays a key role in determining the ultimate properties of any coating. The synchrotron has proven valuable in determining residual stresses for films as thin as 2.5nm and as thick as 6O microns. New techniques have been developed to achieve ... |
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| High Temperature Fatigue of Structural Ceramics |
09 MAR 95 |
7 pages |
| Authors:
I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The objective of the research effort was to establish a fundamental understanding of high temperature fatigue in structural ceramics. Two additional closely related areas, environmental effect on fatigue and temperature dependence on strength and toughness, were also targeted where basic understanding needed to be acquired. We were successful in establishing a comprehensive framework as the basis for understanding fatigue and fracture over a broad range of temperatures, static/cyclic loading conditions, ... |
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| Grain Refinement and Superplasticity in 5083 Al |
1995 |
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| Authors:
R. Verma; A. K. Ghosh; S. Kim; C. Kim; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | A preliminary investigation of thermomechanical processing of 5083 aluminum plate (al 4.7 percent mg-0.7 percent mn) was undertaken to develop a fine-grain sheet for superplastic forming applications. significant differences in grain size and the extent of superplasticity are seen in hot-rolled vs. cold- rolled sheets, with tensile elongations exceeding 600 percent for the cold- rolled alloy. additionally, a separate fine-grain sheet of the same alloy, produced by alusuisse co., was ... |
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| Characterization of the High Temperature Dislocation Substructure of MoSi2 |
1995 |
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| Authors:
J. P. Campbell; H. Chang; R. Gibala; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This paper concerned metals in some important way and contained information about, utilized, or discussed these subjects: basic topics: experimental materials and material types: mosi2 materials related terms: burgers vectors, deformation, dimpling, dislocations, edge dislocations, grain size, plastic strain, polycrystalline, screw dislocations, silicon addition, slip, strain rate, stress strain data, tem parameter values relevant to the data: temp 1200 c and above, temp 900 to 1199 c testing and test ... |
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| Measurement of Interfacial Shear Properties of Composites of Ti-1100 Alloy Reinforced With SCS-6 SiC Monofilament Fiber. |
1995 |
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| Authors:
R. Verma; A. K. Ghosh; H. Merrick; T. Mukherji; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The commonly used thin-slice fiber push-out or pull-out tests to measure interface properties of fiber-reinforced metal-matrix composites can introduce biaxial bending of metallic matrix around the fiber and generate complex interfacial stress states. these factors complicate the interpretation of results from these tests. also, the results from a single fiber push-out (or pull-out) test might not directly relate to the shear properties associated with an assemblage of fibers as in ... |
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| High-Temperature Deformation of B2 NiAl-Base Alloys |
1994 |
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| Authors:
In-Gyu Lee; Amit K. Ghosh; Ranjan Ray; Sunil Jha; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The high-temperature deformation behavior of three rapidly solidified and processed nial-base alloys--nial, nial containing 2 pct tib(sub 2), and nial containing 4 pct hfc--have been studied and their microstructural and textural changes during deformation characterized, compression tests were conducted at 1300 and 1447 k at strain rates ranging from 10-6 to 10-2s-1. hfc-containing material showed dispersion strengthening as well as some degree of grain refinement over nial, while tib(sub 2) ... |
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| Effect of Dopants on Zirconia Stabilization-An X-Ray Absorption Study: I, Trivalent Dopants |
94 |
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| Authors:
Ping Li; I-Wei Chen; James E. Penner-Hahn; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Local atomic structures of Zr and dopant cations in zirconia solid solutions with Fe2O3, Ga2O3, Y2O3, and Gd2O3 have been determined. The Zrions in both partially stabilized tetragonal and fully stabilized cubic zirconia have their own characteristic structures which are dopant-independent. The dopant cations substitute for Zr ions despite severe local distortions necessitated by the large difference in dopant-O distance and Zr-O distance. Dopant ionic size determines the preferred locations ... |
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| Fatigue Crack Growth of Silicon Nitride at 1400 Degrees C: A Novel Fatigue-Induced Crack-Tip Bridging Phenomenon |
94 |
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| Authors:
Shih-Yu Liu; I-Wei Chen; Tseng-Ying Tien; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| A high-strength Si3N4 with elongated beta-Si3N4 and equiaxed alpha prime-sialon was tested in cyclic and static fatigue at 1400 C. At low stress intensity factors and high frequencies, the pullout process of the elongated grains was enhanced, which suppressed the crack growth. This provides a possible explanation for the increased lifetime under cyclic loading conditions reported for ceramics by several investigators. While crack-healing by high- temperature annealing was found to ... |
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| Reaction Hot Pressing of Alpha'- and Beta'-SiAlON Ceramics |
94 |
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| Authors:
Shyh-Lung Hwang; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Hot pressing kinetics of alpha-Si3N4, AlN, Al2O3, and Y2O3 powder mixtures forming alpha prime- and beta prime-SiAlONs have been studied. Densification proceeds in two steps, first by a small shrinkage upon ternary eutectic oxide melting (SiO2-Al2O3-Y2O3) at 1340C, followed by a massive particle rearrangement and further shrinkage at higher temperature when nitride dissolution begins. With better wettability, AlN initially traps the oxide melt and delays densification. In addition, the preferential ... |
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| Microstructural Mechanics Model of Anisotropic-Thermal-Expansion-Induced Microcracking |
94 |
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| Authors:
Narayanaswamy Sridhar; Wuhua Yang; David J. Srolovitz; Edwin R. Fuller Jr; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Thermal-expansion-induced microcracking in single-phase ceramics has been simulated using a simple mechanics model based upon a regular lattice of brittle, elastic springs. Microcracks preferentially form at grain boundaries, propagate either into the bulk or along grain boundaries, depending on the toughness of the boundaries relative to the grain interiors. The present results show that anisotropic-thermal-expansion-induced microcracking can be more severe for either large or small grain size samples depending on ... |
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| Mechanical and Environmental Factors in the Cyclic and Static Fatigue of Silicon Nitride |
94 |
|
| Authors:
David S. Jacobs; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The effects of environment on cyclic and static fatigue behavior were investigated with hot-pressed silicon nitride materials. Tests were conducted at ambient temperature on standard compact tension specimens, and a dc electric potential technique was used to monitor crack lengths in situ. The results indicate that the environmental sensitivity of our materials under both cyclic and static loading mirrors that of durable glasses in static fatigue. The materials were most ... |
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| Nucleation and Growth of Alpha'-SiAlON on Alpha-Si3N4 |
94 |
|
| Authors:
Shyl-Lung Hwang; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Morphology, composition, and growth defects of alpha prime-SiAlON have been studied in a fine-grained material with an overall composition Y(0.33) Si(10)Al2ON(15) prepared from alpha-Si3N4, AlN, Al2O3, and Y2O3 powders. TEM analysis has shown that fully grown alpha prime-SiAlON grains always contain an alpha-Si3N4 core, implicating heterogeneous nucleation operating in the present system. The growth of mode is epitaxial, despite the composition and lattice parameter difference between alpha-Si3N4 and alpha prime-SiAlON. ... |
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| Nucleation and Growth of Beta'-SiAlON |
94 |
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| Authors:
Shyh-Lung Hwang; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Elongated beta prime-SiAlON grains grown from several fine-grained Y(m/3)Si(12-m+n)Al(m+n)O(n)N(16-n) compositions with alpha-Si3N4, AlN, Al2O3, and Y2O3 starting materials have been examined. These grains have large aspect ratios and are oriented along the 0 0 0 1 axis. TEM structural and chemical analysis suggests that they are nucleated from various seed crystals, which can be alpha-Si3N4, beta-Si3N4, or other beta prime-SiAlON. The beta prime-SiAlON seed and the initial precipitation on beta-SiAlON ... |
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| Fibrous Monolithic Ceramics: III, Mechanical Properties and Oxidation Behavior of the Silicon Carbide/Boron Nitride System |
94 |
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| Authors:
Suresh Baskaran; John W. Halloran; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Fibrous monolithic ceramics were fabricated in the SiC/BN system. The microstructure consists of high-aspect-ratio polycrystalline cells of SiC separated by cell boundaries of BN. The fibrous monolithic with aligned cells fails non-catastrophically in flexure, with delamination cracking along the BN cell boundaries. Indentations cause controlled damage on the surface, but no strength-degrading flaws. The flexural strength is in the range 300-375 MPa, and the estimated shear strength is approx. 14 ... |
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| Fibrous Monolithic Ceramics: IV, Mechanical Properties and Oxidation Behavior of the Alumina/Nickel System |
94 |
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| Authors:
Suresh Baskaran; Stephen D. Nunn; John W. Halloran; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Fibrous monolithic ceramics were fabricated in the alumina/nickel system. The microstructure consists of high-aspect-ratio polycrystalline cells of alumina separated by thin cell boundaries of nickel. The nickel content in the material is 3 to 8 vol%. The fibrous monolith with uniaxially aligned cells fails noncatastrophically in flexure. Bridging ligaments of nickel, crack deflection along cell boundaries, and crack branching in the axial direction are observed in flexure bars and notched ... |
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| Superplastic Forming of SiAlON Ceramics. |
1994 |
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| Authors:
Shyh-Lung Hwang; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Superplastic SiAlONs of the nominal composition Y(m/3)-Si(12-(m+n))Al(m+n)O(n)N(16-n) are reported in this study using a transient-phase-forming approach. They encompass the fields of single-phase alpha'-SiAlON, single-phase beta'-SiAlON, and their two-phase mixtures. Excellent formability is obtained at 1550 C for the beta' and alpha' + beta' materials, and at 1600 C for the alpha' material. Typically in the nonequilibrium state before deformation, these fine-grained materials undergo dramatic phase and microstructure evolutions during superplastic ... |
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| Temperature-Time Texture Transition of Pb(Zr(1-x)Ti(x))O3 Thin Films: I, Role of Pb-Rich Intermediate Phases. |
1994 |
|
| Authors:
San-Yuan Chen; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Lead-rich intermediate phases, in particular Pt(5-7)Pb and PbO, are found to form on Pt(111) atop Ti-buffered Si substrates prior to formation of Pb(Zr(1-x)Ti(x))O3 (PZT) thin films. Pt(5-7)Pb is a 111 textured transient intermetallic phase that nucleates PZT111 texture. PbO is a 001 textured layer compound that nucleates PZT100 texture. The formation conditions and lattice matching of these intermediate phases have been examined. The presence of other possible intermediate phases, such ... |
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| Temperature-Time Texture Transition of Pb(Zr(1-x)Ti(x))O3 Thin Films: II, Heat Treatment and Compositional Effects. |
1994 |
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| Authors:
San-Yuan Chen; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Texture transition of Pb(Zr(1-x)Ti(x))O3 thin films grown from a metallo-organic solution onto Pt/Ti/SiO2/Si substrates has been studied. The orientation obtained depends on the crystallization temperature and time and can be dreastically altered by modifying the heat treatment schedule. A 100 texture requires an initial seeding treatment in the intermediate temperature range. This is attributed to a nucleation advantage associated with the formation of an intermediate PbO001 texture that tends to ... |
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| Microstructure and Mechanical Properties of the In Situ Beta-Si3N4/Alpha'-SiAlON Composite. |
1994 |
|
| Authors:
Tzer-Shin Sheu; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The in situ beta-Si3N4/alpha prime-SiAlON composite was studied along the Si3N4-Y2O3:9AlN composition line. This two-phase comjposite was fully densified at 1780C by hot pressing. Densification curves and phase developments of the beta-Si3N4/alpha prime-SiAlON composite were found to vary with composition. Because of the cooperative formation of alpha prime-SiAlON and beta-Si3N4 during its phase development, this composite had equiaxed alpha prime-SiAlON (^0.2 microns) and elongated beta-Si3N4 fine grains. The optimum mechanical ... |
|
| Plasticity-Induced Fatigue Damage in Ceria-Stabilized Tetragonal Zirconia Polycrystals. |
1994 |
|
| Authors:
Shih-Yu Liu; I-Wei Chen; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Current studies on the fatigue lifetime of ceramics are mostly focused on the relation between the stress amplitude (or maximum stress) and cycles to failure. For a more compliant and plastic ceramic which has a pronounced nonlinear stress-strain relation, the role of plastic strain in the fatigue damage is investigated for the first time in this study using 12 mol% Ce-TZP. By testing at different temperatures, we were able to ... |
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| Microstructural Analysis and High-Temperature Strength of a Directionally Solidified Er2Mo3Si4-MoSi2 Eutectic. |
1994 |
|
| Authors:
D. K. Patrick; D. C. Van Aken; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This paper concerned mmc in some important way and contained information about, utilized, or discussed these subjects: basic topics:, data, imc, mmc, mmc data, imc data materials and material types:, (er2mo2si4)2/mosi2, er2mo2si4/mosi2, mosi2 matrix material characteristics and data fields:, hardness data, plasticity, stress-strain data, vicker microhardness parameter values relevant to the data:, 0 c - 100 c, 100 c - 200 c, 1000 c - 1100 c, 1100 c - ... |
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| Plasticity Enhancement Processes in MoSi2-Base Materials. |
1994 |
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| Authors:
R. Gibala; H. Chang; C. M. Czarnik; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Low temperature plasticity enhancement processes observed in body- centered cubic metals and B2 ordered alloys can be observed in MoSi2 in appropriate stress-temperature-strain rate regimes. We illustrate effects of surface films (ZrO2) and dispersoids (TiC) in enhancing plasticity of MoSi2 in the ductile-to-brittle transition range of temperatures, 900-1400 C. We also show, through experiments involving high temperature (1300 C) prestrain, that effective operation of dislocation generation processes can extend the ... |
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| Plasticity of MoSi2 Below 900 C. |
1994 |
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| Authors:
H. Chang; R. Gibala; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The mechanical behavior of polycrystalline MoSi2 tested in compression at temperatures from 750 C to 950 C has been investigated. This material can be deformed to several percent strain without fracture at temperatures as low as 900 C. This same material prestrained at 1300 C and subsequently tested at lower temperatures can be deformed to substantial strain at 800 C, and even exhibits modest plasticity at 750 C. Both prestrained ... |
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| The Effect of Grain Size and SiC Particulates on the Strength and Ductility of MoSi2. |
1994 |
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| Authors:
Amit K. Ghosh; Ajoy Basu; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Monolithic mosi2 and mosi2 reinforced with sic particulate reinforcements have been produced with widely varying grain sizes. monotonic compression behavior of these materials has been examined in the temperature range of room temperature to 1200 c. based on these results, the ductile-to-brittle transition temperature at low deformation rate of mosi2 and its composite appears to be near 900 c and may decrease slightly with decreasing grain size. tension and compression ... |
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| Thermal Fatigue of MoSi2 and MoSi2-10 Vol Percent TiC Composite. |
1994 |
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| Authors:
M. T. Kush; J. W. Holmes; R. Gibala; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Induction heating of disk shaped specimens was used to study thermal fatigue behavior of hot pressed mosi2, hot pressed and hot isostatically pressed (hiped) mosi2, and mosi2-10 vol% tic particulate composite. specimens were subjected to 5s, 30s, and 300s heating and cooling cycles between temperature limits of 700 c and 1200 c. specimens of both the hot pressed and the hot pressed and the hiped polycrystalline mosi2 material failed by ... |
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| Particle Size, Volume Fraction and Matrix Strength Effects on Fatigue Behavior and Particle Fracture in 2124 Aluminum-SiCp Composites. |
1994 |
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| Authors:
Jody N. Hall; J. Wayne Jones; Anil K. Sachdev; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The effects of particle size, volume fraction and matrix strength on the stress-controlled axial fatigue behavior and the probability of particle fracture were evaluated for 2124 aluminum alloy reinforced with sic particles. average particle sizes of 2, 5, 9 and 20 micrometer and volume fractions of 0.10, 0.20 and 0.30 were examined for four different microstructural conditions. tensile and yield strengths and fatigue life were substantially higher in the reinforced ... |
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| Deformation Behavior of Gamma-TiAl Composites in the Solid and Mushy States. |
1994 |
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| Authors:
K. Makhlouf; A. K. Ghosh; R. Ray; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The deformation behavior of a two phase (gamma+alpha(sub)2) laminar tial reinforced with various amounts of alti2c carbide platelets has been examined by determining vickers hardness at room temperature and in the temperature range 900-1300 c the compression flow behavior of these materials has also been examined in the semi-solid state the hardness values for all materials dropped from about 4 gpa at room temperature to 120 mpa at 1300 c ... |
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