85 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Stacking Faults"

open access

Hydrogen embrittlement of austenitic stainless steels

No Description Available.

Date: January 1, 1974

Creator: Louthan, M. R. Jr.; Rawl, D. E. Jr.; Donovan, J. A. & Holmes, W. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Secondary defects in quenched platinum

The structure of secondary defects in two different platinum purities quenched under ultra high vacuum, has been studied by transmission electron microscopy. Faulted loops on (100) planes have been observed in both materials. In the less pure platinum, Pt B (but purer in terms of carbon content), the defects were observed after quenching, whereas in the purest one, Pt A (but less pure in terms of carbon content), the defects were formed after a long annealing. The Burgers vector of the loops fo… more

Date: November 1, 1979

Creator: Perez, M.I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Effect of annealing on the substructure of cold worked FCC metals and alloys. Final report, January 1, 1965--December 31, 1974

No Description Available.

Date: January 1, 1974

Creator: Mikkola, D.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Atom-probe field-ion microscope study of the stoichiometry of ordered Ni/sub 4/Mo

Atom-probe field-ion microscope analyses were performed on specimens of ordered Ni/sub 4/Mo. The (211) fundamentl and (101) superlattice planes of the body-centered tetragonal (BCT) lattice were analyzed chemically on a layer-by-layer basis. In the case of (211)/sub BCT/ fundamental planes the chemistry of each individual plane was determined as a function of depth; for eight successive (211)/sub BCT/ layers an average Mo concentration of 17.2 at. % was measured - as compared to 19.4 at. % Mo b… more

Date: May 1980

Creator: Yamamoto, Masahiko & Seidman, David N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transmission Electron Microscopy Study of Nonpolar a-Plane GaNGrown by Pendeo-Epitaxy on (112_0) 4H-SiC

Pendeo-epitaxy has been applied to nonpolar a-plane GaN layers in order to observe if such process will lead to defect reduction in comparison with direct growth on this plane. Uncoalesced and coalesced a-plane GaN layers with thicknesses 2{micro}m and 12{micro}m, respectively have been studied by conventional and high resolution electron microscopy. The following structural defects have been observed in pendeo-epitaxial layers: (1) basal stacking faults, (2) threading dislocations and (3) pris… more

Date: March 10, 2005

Creator: Zakharov, D. N.; Liliental-Weber, Z.; Wagner, B.; Reitmeier, Z. J.; Preble, E. A. & Davis, R. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atomically engineering Cu/Ta interfaces.

This report summarizes the major research and development accomplishments for the late start LDRD project (investment area: Enable Predictive Simulation) entitled 'Atomically Engineering Cu/Ta Interfaces'. Two ultimate goals of the project are: (a) use atomistic simulation to explore important atomistic assembly mechanisms during growth of Cu/Ta multilayers; and (b) develop a non-continuum model that has sufficient fidelity and computational efficiency for use as a design tool. Chapters 2 and 3… more

Date: September 1, 2007

Creator: Webb, Edmund Blackburn, III & Zhou, Xiao Wang

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates

Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the 'seed' area and wing area was detected by Convergent B… more

Date: January 5, 2006

Creator: Liliental-Weber, Z.; Ni, X. & Morkoc, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atomistically-informed Dislocation Dynamics in fcc Crystals

We develop a nodal dislocation dynamics (DD) model to simulate plastic processes in fcc crystals. The model explicitly accounts for all slip systems and Burgers vectors observed in fcc systems, including stacking faults and partial dislocations. We derive simple conservation rules that describe all partial dislocation interactions rigorously and allow us to model and quantify cross-slip processes, the structure and strength of dislocation junctions and the formation of fcc-specific structures s… more

Date: September 6, 2006

Creator: Martinez, E.; Marian, J.; Arsenlis, T.; Victoria, M. & Perlado, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dislocation-Radiation Obstacle Interactions: Developing Improved Mechanical Property Constitutive Models

The objective of this program was to understand the interaction of dislocations with a wide range of obstacles commonly produced in materials under irradiation (dislocation loops, voids, helium bubbles, stacking fault tetrahedra and radiation-induced precipitates). The approach employed in this program combined multi-scale modeling and dynamic in-situ and static ex-situ transmission electron microscopy experiments.

Date: October 10, 2008

Creator: Robertson, Ian

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Advanced Branching Control and Characterization of Inorganic Semiconducting Nanocrystals

The ability to finely tune the size and shape of inorganic semiconducting nanocrystals is an area of great interest, as the more control one has, the more applications will be possible for their use. The first two basic shapes develped in nanocrystals were the sphere and the anistropic nanorod. the II_VI materials being used such as Cadmium Selenide (CdSe) and Cadmium Telluride (CdTe), exhibit polytypism, which allows them to form in either the hexagonally packed wurtzite or cubically packed zi… more

Date: December 31, 2007

Creator: Hughes, Steven Michael

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Dynamic Response of Copper Subjected to Quasi-Isentropic, Gas-Gun Driven Loading

A transmission electron microscopy study of quasi-isentropic high-pressure loading (peak pressures between 18 GPa and 52 GPa) of polycrystalline and monocrystalline copper was carried out. Deformation mechanisms and defect substructures at different pressures were analyzed. Current evidence suggests a deformation substructure consisting of twinning at the higher pressures and heavily dislocated laths and dislocation cells at the intermediate and lower pressures, respectively. Evidence of stacki… more

Date: September 29, 2005

Creator: Jarmakani, H.; McNaney, J. M.; Schneider, M. S.; Orlikowski, D.; Nguyen, J. H.; Kad, B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Material dynamics under extreme conditions of pressure and strain rate

Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under t… more

Date: September 6, 2005

Creator: Remington, Bruce A.; Allen, Patrick; Bringa, Eduaro; Hawreliak, Jim; Ho, Darwin; Lorenz, K. Thomas et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A forest model of latent hardening and its application to polycrystal deformation

This paper means to assess latent hardening effects on large-scale polycrystal deformation on the basis of the dislocation theory of plastic flow and of a wide variety of experimental observations on single crystals. The qualifier large-scale is introduced to eliminate effects during the earliest stages of flow, where mono- and polycrystals behave differently: the authors will not consider easy glide in single crystals; and they will not consider the gradual transition, over perhaps ten times t… more

Date: January 1, 1990

Creator: Kocks, U.F. (Los Alamos National Lab., NM (USA)); Franciosi, P. (Paris-13 Univ., 93 - Villetaneuse (France)) & Kawai, M. (Tsukuba Univ., Ibaraki (Japan). Inst. of Engineering Mechanics)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Total energy calculations and bonding at interfaces

Some of the concepts and theoretical techniques employed in recent ab initio studies of the electronic and structural properties of surfaces and interfaces are discussed. Results of total energy calculations for the 2 x 1 reconstructed diamond (111) surface and for stacking faults in Si are reviewed. 30 refs., 8 figs.

Date: August 1, 1984

Creator: Louie, S.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Annealing of interstitial loops in arsenic implanted silicon

The annealing effect of different gas ambient (N/sub 2/ or O/sub 2/) on high dose (5 x 10/sup 15/) As-ion-implanted Si wafer has been investigated by using transmission electronic microscope. A two-layer defect structure is observed. The lower layer defects are interstitial type and attributed to the amorphous island below original crystalline-amorphous interface. The upper layer loops are As precipitation in the form of stacking fault. By comparing the growth/shrinkage rate of interstitial loo… more

Date: May 1, 1983

Creator: Wu, N. R.; Ling, P.; Sadana, D. K.; Washburn, J. & Current, M. I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evidence for stacking faults in multiaxial strained alpha-brass

Two different techniques of x-ray diffraction have been applied to the examination of multiaxial strained alpha-brass. From an examination of the unfolded Fourier coefficients describing the shape of the diffraction profile it has been determined that the true crystallite size probably exceeds 2000 A, a practical upper limit for determining crystallite size by x-ray methods. The localized strain is approximately 0.225% and a combined stacking fault probability (1.5 ..cap alpha..' + ..beta..) = … more

Date: January 1, 1983

Creator: Roof, R.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Microstructural studies of advanced austenitic steels

This report presents the first complete microstructural and analytical electron microscopy study of Alloy AX5, one of a series of advanced austenitic steels developed by Maziasz and co-workers at Oak Ridge National Laboratory, for their potential application as reheater and superheater materials in power plants that will reach the end of their design lives in the 1990's. The advanced steels are modified with carbide forming elements such as titanium, niobium and vanadium. When combined wit… more

Date: November 15, 1989

Creator: Todd, J. A. & Ren, Jyh-Ching

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Shock wave effects and metallurgical parameters

This review summarizes results from some principal investigations of shock-strain effects in metals. The strain contribution indeed plays a role in residual microstructures, particularly, if the strain becomes dominant as in ''under trapped'' experiments of low or moderate pressure or for that matter, of ''well trapped'' high pressure experiments. Not only does this strain contribution affect the microstructure by increasing deformation, a concommitant strain heat is generated and absorbed by t… more

Date: May 18, 1987

Creator: Staudhammer, K.P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Molecular modeling of metal hydrides: 2. Calculation of lattice defect structures and energies utilizing the Embedded Atom Method

Lattice defect structures and energies for palladium, nickel and aluminum computed include: single vacancy, self-interstitial, intrinsic stacking fault, coherent twin boundary and (100), (110), and (111) free surfaces. The importance of considering lattice defects in obtaining an accurate Embedded Atom Method (EAM) description of real materials, and the application of the EAM to the computation of lattice defect structures for palladium, nickel and aluminium is discussed. The EAM functions deve… more

Date: December 1, 1990

Creator: Wolf, R.J. & Mansour, K.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

EBIC and HVTEM studies of RTR silicon ribbon

The defect structure of RTR ribbon No. 6-731, run 803 was studied by CTEM, EBIC and HVTEM. Prior to laser recrystallization the defect structure consists of closely spaced twin and grain boundaries. Precipitation of impurities occurs after laser recrystallization. The observation of electrically active defects in EBIC has been correlated with HVTEM studies Pairs of electrically active defects in twin boundaries are due to stacking faults connecting the twin boundaries.

Date: April 1, 1981

Creator: Cunningham, B.; Strunk, H. & Ast, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ion beam synthesis of SiGe alloy layers

Procedures required for minimizing structural defects generated during ion beam synthesis of SiGe alloy layers were studied. Synthesis of 200 mm SiGe alloy layers by implantation of 120-keV Ge ions into <100> oriented Si wafers yielded various Ge peak concentrations after the following doses, 2{times}10{sup 16}cm{sup {minus}2}, 3{times}10{sup 16}cm{sup {minus}2} (mid), and 5{times}10{sup 16}cm{sup {minus}2} (high). Following implantation, solid phase epitaxial (SPE) annealing in ambient N2 at 8… more

Date: May 1, 1994

Creator: Im, Seongil

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

The processing and potential applications of porous silicon

Stability of a cylindrical pore under the influence of surface energy is important for porous silicon (PS) processing in the integrated circuit industry. Once the zig-zag cylindrical pores of porous silicon or oxidized porous silicon (OPS) are unstable and breakup into rows of isolated spherical pores, oxidation of PS and densification/nitridation of OPS become difficult. Swing to difficulty transport of reactant gas (O{sub 2}, NH{sub 3}) or the trapped gas (for densification of OPS). A first o… more

Date: July 1, 1992

Creator: Shieh, Syyuan

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Synthesis of Novel Extended Phases of Molecular Solids at High Pressures and Temperatures

This study is for in-situ investigation of chemical bonding and molecular structure of low z-elements and simple molecular solids at high pressures and temperatures using 3rd-generation synchrotron x-ray diffraction. To understand the contribution of the empty d-electron orbital of Mg in relation to the formation of molecular solids like MgO, which is one of the important Earth lower mantle materials and MgB{sub 2}, which has recently been the focus of intense superconducting material research,… more

Date: March 30, 2004

Creator: Yoo, C; Evans, W & Cynn, H

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Channeling analysis of stacking defects in epitaxial Si layers

The channeling effect technique has been applied to investigate dechanneling by stacking defects in heteroepitaxially grown silicon. Ion backscattering was performed on 0.9 ..mu..m Si layers grown on sapphire as a function of beam energy (1.1 to 2.5 MeV He/sup +/), projectile ion (He/sup +/, D/sup +/) and crystal direction ((100), (111), (112), (113)). A model based on the new interior surfaces presented by such stacking defects is used to calculate the dechanneling cross section, and the disor… more

Date: January 1, 1977

Creator: Campisano, S. U.; Foti, G. & Rimini, E.

Item Type: Article

Partner: UNT Libraries Government Documents Department