... of the platelike grains was favored in compacts with a small grain size and with a narrow size distribution at the onset of abnormal grain growth. ...
DTIC Science & Technology
... Title : ABNORMAL GRAIN GROWTH BEFORE THE MELTING TRANSITION AND SUBSEQUENT STRUCTURAL CHANGE OF VACUUM ...
... Accession Number : AD0426010. Title : ABNORMAL GRAIN GROWTH IN ALUMINUM AND ITS ALLOYS: AN ANNOTATED BIBLIOGRAPHY,. ...
abnormal growth to a larger grain size. His explanation of the effect . . 54 " of sintering additives is their, delay of abnormal growth :.:"- ...
NASA Website
Abnormal Grain Growth in Alumina: Synergistic Effects of Yttria and Silica Ian MacLaren Technische Stuttgart, Germany Abnormal grain growth without strong anisotropy or faceting of the grains has been remains self-similar. During ...
E-print Network
... Title : The Abnormal Grain Growth and Dielectric Properties of (Nb, Ba) Doped TiO2 Ceramics. Descriptive Note : Journal article,. ...
... Title : Abnormal Grain Growth of ODS Superalloys Enhanced by Boron Doping or Torsional Strain,. Descriptive Note : Conference Paper,. ...
... Title : Abnormal Grain Growth in Oxide Dispersion Strengthened Ni-Base Superalloy. Descriptive Note : Journal article,. ...
... Accession Number : AD0179985. Title : ABNORMAL GRAIN GROWTH IN TD-NICKEL. Corporate Author : Personal Author ...
1 Abnormal Grain Growth and Texture Development A.D. Rollett Materials Science & Engineering: Abnormal grain growth, theory, texture development, iron-silicon alloys. Abstract. A theory for abnormal they may account for abnormal ...
Abnormal grain growth was found in sintered Nd-Fe-B magnets which are made from powder milled after hydrogen decrepitation. The abnormal grain size in the magnets sintered at 1000 {degree}C for 1.5 h was as large as 400 {mu}m. The formation of abnormally large ...
Energy Citations Database
1 Microstructure evolution and abnormal grain growth during copper wafer bonding K. N. Chen, A. Fan after post-bonding anneal. An abnormal (220) grain growth was observed during the initial bonding are analyzed. It is surprising that there is an ...
... CORPORATE RESEARCH AND DEVELOPMENT SCHENECTADY NY. ... ARGON, GRAIN GROWTH, ABNORMALITIES, CUTTING, CANTILEVER ...
During abnormal grain growth (AGG) or secondary recrystallization, some small grains are entrapped in the growing large grains and become island grains. In this report, the authors describe the observations of island grains formed during annealing of ...
... ohm cm and eliminated exaggerated grain growth of ... is the reduction in critical flaw size. ... flaw population associated with abnormally large grains. ...
This paper reports a study of abnormal grain growth in tungsten ingots that had been deformed in compression at elevated temperatures. The results show that very large grains form in these samples directly from the polygonized structure when the deformed samples are annealed. A critical amount of deformation is ...
The origin of recrystallization nuclei is reviewed with particular emphasis on materials in which well-developed cells are present in the deformed state. Nucleation is discussed in terms of coarsening of the subgrain network that develops on annealing and an analogy is made with abnormal grain growth. The results of a theoretical ...
DOE Information Bridge
Ltd. All rights reserved. Keywords: Electron backscatter diffraction; Abnormal grain growth; Island grains; Boundary character; Low mobility Studies of the phenomenon of abnormal grain growth (AGG) have embedded in abnormally ...
Biaxial stress and strain in (100) and (111) oriented grains have been measured as a function of annealing temperature for a Cu film on an oxidized Si substrate which exhibits abnormal (100) grain growth. The observed behavior indicates isostrain averaging, which is consistent with grain ...
Abnormal grain growth is characterized by the lack of a steady state grain size distribution. In extreme cases, the size distribution becomes transiently bimodal, with a few grains growing much larger than the average size. This is known as secondary grai...
National Technical Information Service (NTIS)
Boron carbide compacts sintered between 2220/sup 0/ and 2250/sup 0/C showed abnormal grain growth that was associated with twinning and microcracking. The twin direction was (011). The microcracking was linked to thermal expansion anisotropy determined by high-temperature lattice constant measurement.
... Title : Abnormal Grain Growth in Al-Mg (6 to Approximately 8%) Alloys Containing Under 0.4% of Mn and Cr--Secondary Recrystallization of ...
This paper presents a contribution to the theory of abnormal grain growth in two dimensions by considering an idealized model with both a variable boundary energy and a variable mobility. The authors idealize the problem by considering a single A grain in a matrix of B grains where the AB ...
The abnormal grain growth of austenite was studied in a commercial steel of composition (wt%): 0.70 C, 1.36 Mn, 0.72 Si, 0.015 P, 0.027 S and 0.03 Nb. Specimens were thermocycled at various conditions and then grain size distribution determined. The grain size distribution shape did not change ...
... The primary objectives of this program were to investigate the conditions leading to the abnormal grain growth behavior in Rene 95 extrusions, and ...
. Cockayne and M. Hoffmann, "Abnormal Grain Growth in Undoped Strontium and Barium Titanate", Acta Materialia
Other frequent errors are abnormal small-grain signatures and estimates made without sufficient representations of necessary growth stages of small grains. ...
... Single crystals of refractory metal alloys are usually produced by electron beam zone melting, since it is difficult to develop large grain crystals by ...
identified a robust link connecting singular surfaces to abnormal coarsening and grain growth phenomena. Based on this work, abnormal growth can be attributed to the step migration growth mechanisms population. Furthermore, the growth constant (K in Eq. ...
During liquid phase sintering, cemented carbide particles grow into either faceted or non-faceted grain shapes depending on ally system. In case of WC-Co alloy, prism-shape faceted grains with (0001) planes and {l_brace}1{bar 1}00{r_brace} planes on each face are observed, and furthermore an abnormal grain ...
Grain growth during annealing of polycrystalline materials is influenced by the type of grain boundaries a grain encounters as it grows. Simple computer experiments have been performed to ascertain which type of boundaries are responsible for the abnormal grain ...
The effect of crystal phase in the starting powder of (Ba,Nb)-doped TiO{sub 2} ceramics on abnormal grain growth was investigated. The abnormal grain growth took place mainly during the cooling period after the second phase precipitated. The extent of ...
The present investigation is concerned with analytical modelling of grain growth in metals and alloys in the presence of growing and dissolving precipitates. In Part 2 the modelling methodology presented in Part 1 for normal grain growth has been further developed and applied to abnormal ...
Thin nanostructured gold films were deposited on SiO{sub 2} by the sputtering technique at room temperature. Films of different thicknesses were deposited ranging from 2 to 16 nm. The film morphology as a function of the thickness was analyzed by microscopic techniques such as atomic force microscopy and transmission electron microscopy. These analyses allowed us to clarify the ...
Non-Sag tungsten (W) wire is indispensable for the lighting industry. For the necessary creep resistance, large elongated grains are considered as the desired microstructure. These large grains are obtained by primary and secondary recrystallization. In the present study an effort has been made to characterize and to understand the origin of such large ...
The development of texture in barium hexaferrite by templated grain growth was studied as a function of the Fe2O3/BaCO3 ratio, B2O3 additions in the starting materials, and sintering temperature. A magnetic field was used to orient the template particles during the gelcasting process. Excess BaCO3 resulted in abnormal ...
Abnormally large grains have been observed in Al-Mg alloy AA5182 sheet material after forming at elevated temperature, and the reduced yield strength that results is a practical problem for commercial hot-forming operations. The process by which abnormal grains are produced is investigated through controlled hot ...
NASA Astrophysics Data System (ADS)
Evolution of microstructure morphologies and grain orientations of Cu-Cu bonded wafers during bonding and annealing were studied by means of transmission electron microscopy, electron diffraction, and x-ray diffraction. The bonded Cu grain structure reaches steady state after post-bonding anneal. An abnormal (220) ...
Normal and abnormal grain growth evolution of a two-dimensional network of 1024 grains is investigated using a computer simulation based on the variational principle derived in Part 1 of this paper. A brief overview of normal grain growth theories is presented and the ...
X-ray reciprocal-space mapping and atomic force microscopy (AFM) are used to study kinetics and mechanisms of lateral grain growth in epitaxial (001) ceria (CeO{sub 2}) deposited by pulsed laser deposition on (001) yttria-stabilized zirconia (YSZ) and (12 lowbar 10) (r-cut) sapphire. Rate and character of the grain ...
X-ray reciprocal-space mapping and atomic force microscopy (AFM) are used to study kinetics and mechanisms of lateral grain growth in epitaxial (001) ceria (CeO2) deposited by pulsed laser deposition on (001) yttria-stabilized zirconia (YSZ) and (12&barbelow;10) ( r -cut) sapphire. Rate and character of the grain ...
Controlled laboratory experiments were carried out on samples or bar stock of air- and vacuum-melted Waspalloy, Inconel X-550, and Nimonic 80A alloys to find conditions of heating and hot-working which resulted in abnormal grain growth. These experiments were mainly limited to normal conditions of heating for hot-working and ...
... Abstract : The effects of MgO on sintering and grain growth of alumina in the ... alumina and sintering at 1900 C for 1 h in a clean contamination-free ...
The effect of powder characteristics on the microstructures and dielectric properties of (Ba,Nb)-doped TiO{sub 2} ceramics was investigated. Two powders were prepared: one by coprecipitation and the other from mixing of reagent oxides. The powder characteristics were determined by TEM, x-ray powder diffraction, SEM, and centrifugal particle analysis. Extensive abnormal ...
Abnormal grain growth is characterized by the lack of a steady state grain size distribution. In extreme cases, the size distribution becomes transiently bimodal, with a few grains growing much larger than the average size. This is known as secondary grain ...
A nickel alloy, Waspaloy, with an equiaxed microstructure and random texture was studied to examine its grain growth behavior and, in particular, stagnation of growth via precipitate pinning. The grain growth kinetics matched the model developed by Anderson and Grong [1] during the early stages ...
Thirty-seven references on abnormal grain growth in aluminum and its alloys in the field of critical straining and thermal treatment are presented. Material on the prevention of such growth by seeding'' aluminum alloys with intermetallics is included, as is material on other prevention ...
BaTiO[sub 3] single crystals were prepared by solid-state grain growth. The single crystals were obtained by seeding a polycrystalline, TiO[sub 2]-excess BaTiO[sub 3], which exhibited abnormal grain growth. The condition for single-crystal growth was essentially dependent ...
The present investigation is concerned with analytical modelling of grain growth in metals and alloys in the presence of growing and dissolving precipitates. In Part 1, the different components of the normal grain growth model are outlined and differential equations presented which allow the mean ...
Abnormal grain growth (AGG) is not one of the intrinsic properties of alumina but rather is an extrinsic property that is controlled by certain impurities that are introduced during powder synthesis, processing, or sintering. When small amounts of glass-forming impurities are introduced, some portion beyond their solubility limits will ...
... Abnormal grain growth (grain sizes of 2.8 to 28.5 microns) and densification (porosities of 2% to 12%) are found, and the tetragonality c/a nearly ...
Normal grain growth in 80-nm-thick sputter-deposited Ag films was studied via in situ heating stage transmission electron microscopy. The as-deposited films with an initial grain size of 40-50 nm were held at a series of temperatures (one per specimen) below 250 C. A grain growth exponent n=3 ...
Methods for fabrication of Nb/sub 3/Sn superconductive solenoids are discussed. Problems included embrittlement by hydrogen and abnormal grain growth. Suggestions for solving these problems are offered. Finely divided Al/sub 2/O/ sub 3/ is recommended to inhibit abnormal grain ...
Anisotropic abnormal grain growth in ceramics was simulated by a three-dimensional Monte Carlo computer model. Microstructures similar to experimental ones were obtained and the influence of energy anisotropy and the number of anisotropically growing grains on microstructure development were studied. It was shown ...
In order to study the development of the Goss grain size distribution during grain growth, a 3% silicon-iron industrial material was investigated by different metallographic technics (X-ray analysis, etch-pitting), after decarburization and just before secondary recrystallization. The results show as the special conditions of texture ...
The effects of surface treatment and microstructure, especially abnormal grain growth, on the strength of sintered SiC were studied. The surfaces of sintered SiC were treated with 400, 800 and 1200 grit diamond wheels. Grain growth was induced by increasi...
Abnormal coarsening of austenite ({gamma}) grains occurred in low-alloy steels during a seamless pipe hot-rolling process. Often, the grains became several hundred micrometer in diameter. This made it difficult to apply direct quenching to produce high-performance pipes. The phenomenon of grain coarsening was ...
Data from two simulations on particle limited grain growth are reported. For 3D simulations the same type of strong correlation between particles and grain boundaries previously found in 2D simulations was found with the limiting grain size scaling in 3D with (l/f){sup 0.31}. Very much higher particle correlation ...
Texture alterations accompanying grain growth have been simulated by means of a new statistical model which for the first time takes into account the dependence of both the energy and mobility of grain boundaries on their disorientation. Model polycrystals with a single-component texture are assumed to consist of preferably oriented ...
If the grains dispersed in a liquid matrix are spherical, their surface atomic structure is expected to be rough (diffuse), and their coarsening has been observed to be controlled by diffusion in the matrix. They do not, furthermore, undergo abnormal growth. On the other hand, in some compound material systems, the ...
Metallurgical evaluations were conducted to determine what, if any, grain size differences exist between grit blasted and non-grit blasted DOP-26 iridium alloy cup surfaces and if grit blasting imparts sufficient compressive cold work to induce abnormal grain growth during subsequent temperature exposures. ...
N18 is a new nickel base superalloy produced by powder metallurgy and specifically designed for high temperature turbine disk applications. The goal of the present work is to understand the conditions under which very large grains can grow in PM nickel base superalloy N18 and to identify the mechanisms responsible for this growth. ...
A new concept of interface complexions has recently been proposed. It recognizes grain boundaries as distinct "phases", which have complex and important three-dimensional structure at the atomic level that depends on thermodynamic variables such as composition, temperature, pressure, and crystallographic misorientation. In the present research program, we have performed a ...
The stress effect on microstructure evolution in submicrometer Al dots in confinement has been studied by transmission electron microscopy. Direct observation of grain growth and void formation in the dots, unconfined as well as confined by sputtered quartz, was investigated. In the as-deposited state, most of the grains were larger ...
The effects of MgO on sintering and grain growth of alumina in the absence of any other impurities as well as in the presence of various amounts of CaO were investigated using ultrapure (>99.999%) alumina and sintering at 1,900 C for 1 h in a clean contamination-free condition. Critical concentrations of MgO required for the prevention of ...
It is well recognized that the presence of second phase particles strongly influences grain boundary migration in polycrystalline materials. In this work experiments have been performed to assess the effects of the various different precipitates upon the grain growth behavior in two powder metallurgy (P/M) Ni-base superalloys, IN100 ...
Contents: Nippon steel ironmaking control and data exchange system; Control model of continuous casting machine operation; HT60 Steels by direct quenching method; Prevention of abnormal growth of recrystallized ferrite grains in low-carbon steels wires; E...
The primary objectives of this program were to investigate the conditions leading to the abnormal grain growth behavior in Rene 95 extrusions, and to study the microstructure of AF115 and the effect of hold time conditions on the low-cycle fatigue behavio...
Carlo, computer simulation, abnormal grain growth, nucleation, and recrystallization Abstract behavior during recrystallization both experimentally and analytically [1-6]. The nucleation models for recrystallization are roughly divided into two theories. One is the oriented nucleation (ON) model [1, 2], in which
The origin of recrystallization nuclei is reviewed with particular emphasis on materials in which well-developed cells are present in the deformed state. Nucleation is discussed in terms of coarsening of the subgrain network that develops on annealing and...
When an extruded strain-free REN� 88 Ni-base superalloy about 1 to 2 �m in grain diameter is heattreated at 1150�C, abnormal grain growth (AGG) begins after 50 hours. When heat-treated at 1200 �C, AGG occurs at 15 minutes. Some of the grain boundaries are faceted with hill-and-valley ...
Strontium barium niobate, Sr{sub 0.6}Ba{sub 0.4}Nb{sub 2}O{sub 6} (SBN40) ceramics were prepared by the mixed oxide route; specimens sintered at 1300{degree}C{endash}1450{degree}C for 2{endash}4 h had densities of {approximately}95{percent} theoretical. The use of {open_quotes}conventional{close_quote}{close_quote} conditions (1300{degree}C; {approximately}200{degree}C below the melting ...
The effect of calcia on the grain growth of yttria was investigated in present work. The results shown that by adding calcia, yttria was sintered as low as 1300�C and abnormal grain growth model was observed over 1500�C. When higher than 1600�C, lots of closed pores were formed in the ...
... Title : EFFECTS OF GRAIN SIZE AND GRAIN GROWTH ON THE STRUCTURES OF OXIDE FILMS FORMED ON 18 Cr STEEL,. Corporate Author : ...
For many years, normal or abnormal grain growth phenomena have been modelled using several ways. These methods give statistical results in agreement with the experimental measurements (comparison of the grain growth exponent, average number of neighbors, ...). One should note however that the ...
Skeletal growth is a dynamic process. A knowledge of the structure and function of the normal growth plate is essential in order to understand the pathophysiology of abnormal skeletal growth in various diseases. In this well-illustrated article, the authors provide a radiographic classification of ...
... Title : Grain Growth and Recrystallization in Titanium and Its Alloys. ... Part 2. Grain Growth and Recrystallization Studies. ...
... CONST. AND GRAIN GROWTH DURING SINTERING AT 1300 DEGREE WAS STUDIED. THE RATE OF GRAIN GROWTH ...
A MgO-depletion mechanism is proposed for the Solid State Crystal Conversion (SSCC) phenomenon in MgO-doped A12O3, where sapphire crystals grew up to 5 cm in length by classical abnormal grain growth in microstructures with average grain sizes of 10-45 mi...
Increasingly harsh operation conditions of water reactors, such as high burn-up fuel cycles, demand improved Zr-based alloys for the reactor core applications. Enhanced corrosion resistance, better than that of Zircaloy-4, was realized in the newly developed Zr-based alloys containing Nb and Sn. Zr-Nb alloy was developed for pressure tubes of heavy water reactors while Zr-Nb-Si alloys such as ...
... in K(Sub IC) with increasing grain size arose as a result of the presence of abnormally large grains compared to the average grain size in the large ...
We developed a phase-field model to study the stress-driven grain boundary migration in elastically inhomogeneous polycrystalline materials with arbitrary elastic inhomogeneity and anisotropy. The dependence of elastic stiffness tensor on grain orientation is taken into account, and the elastic equilibrium equation is solved using the Fourier spectral ...
Interfaces are a critical determinant of the full range of materials properties, especially at the nanoscale. Computational and experimental methods developed a comprehensive understanding of nanograin evolution based on a fundamental understanding of internal interfaces in nanocrystalline nickel. It has recently been shown that nanocrystals with a bi-modal grain-size ...
The magnetic and mechanical properties of Nd-Fe-B magnets at different hot deformation temperatures have been investigated. The results showed that the optimum magnetic and mechanical properties and the highest crystallographic alignment of Nd-Fe-B magnets were obtained at 700 �C, and the possible reasons were analyzed. The microstructures show that abnormal ...
A new technique to measure quantitatively grain growth kinetics at high temperatures was presented in this article. This technique, based on the generation and detection of ultrasound using lasers, called laser-ultrasonics, measures the scattering of ultrasonic echoes propagating in a sample to evaluate grain size. A quantitative ...
A novel processing procedure for significantly suppressing grain growth in submicrometer alumina compacts has been developed and implemented with the intent of ultimately using the same processing route to control grain size in nanophase alumina compacts. In this study, partially sintered alumina pellets made from 0.5 {micro}m starting ...
Qaidam basin is a Mesozoic and Cenozoic inland oil basin where the abnormal formation pressure is as developed as in many offshore regions. The abnormal formation pressures are found at depths below 3200 m in relatively depressed regions. Their pressure gradients are from 0.14 to 0.22 atm/m. The causes of abnormal formation pressure in ...
Theories and models for interstellar grain formation and growth, grain alignment and polarization by
NASA Technical Reports Server (NTRS)
Free sintering of SiC with Al, B, and C additions in two successive stages, first under nitrogen and then under argon, produced a near full-density ceramic with equiaxed grain structure. The beta to alpha transformation proceeded to completion; however, the grain shape remained equiaxed due to the action of nitrogen present during the first stage of ...
This paper investigates the effect of tension annealing and of strain annealing on abnormal grain growth (AGG) in polycrystalline rolled sheet of NbC-added Fe81Ga19. Electron backscattering diffraction patterns captured by orientation imaging microscopy were used for analyzing texture and grain configuration of ...
... Title : Anomalous Grain-Size Distributions during Continuous Grain Growth,. ... During the longer annealing times continuous grain growth took place. ...
It has been known that barium titanate (BaTiO3) causes abnormal grain growth during conventional sintering utilizing resistance heating. The grain growth of barium titanate induced using by a hydrothermal synthesis method is controlled using microwave sintering having effects on internal ...
... suppressed large-scale exaggerated grain growth of SiC, and it had a tendency to simulate grain growth with a high aspect ratio of the SiC grains. ...
... stages of grain growth; in the first stage, the grain growth is associated with migration of solute Cu atoms to grain boundaries; grain growth stops as ...
... DISLOCATIONS, EQUATIONS, EVOLUTION(GENERAL), FINE GRAINED MATERIALS, GRAIN BOUNDARIES, GRAIN GROWTH, MAGNESIUM ...
A study of the evolution of recrystallized structure and texture in the surface of a cold rolled twin roll cast AlFeSi alloy is presented. Annealing of such alloys often results in an abnormally coarse grained recrystallized surface structure with a strong cube texture. The evolution of this structure depends on the annealing procedures, that is, the ...
... Title : RECRYSTALLIZATION AND GRAIN GROWTH OF ALUMINUM. Corporate Author : RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ. ...
... ADD116243. Title : RECRYSTALLIZATION AND GRAIN GROWTH IN METASTABLE BETA III TITANIUM ALLOY,. Corporate Author : ...
