Sans Measurements of Deuterium Trapped at Grain Boundaries in Palladium

1993 ◽  
Vol 319 ◽  
Author(s):  
Brent J. Heuser ◽  
John S. King ◽  
George C. Summerfield
Keyword(s):  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Cross Sections ◽  
Cold Working ◽  
Boundary Surface ◽  
Surface Concentration ◽  
Calculated Effect ◽  
Scattering Response

AbstractSmall-angle neutron scattering from grain boundary interfaces has been investigated in polycrystal palladium with and without deuterium dissolved in the solution phase. Polycrystalline samples were prepared using two different procedures: (1) single crystal material was recrystallized at 517°C after 78% cold working, and (2) an extruded polycrystal rod was investigated as received, or recrystallized at 600°C and 680°C. The expected 1/Q2 scattering profile (where Q is the neutron wavevector transfer) from grain boundaries has been observed, and the absolute cross sections permit a determination of the grain boundary surface concentration of missing palladium atoms and of trapped deuterium. The vacancy and trapped deuterium surface concentration determined in these measurements was 0.2-0.3 vacancies/Å2 and 0.4-0.6 deuterons/Å2, respectively. The measurements were extended to the low Q region (Q ≥0.006 1/Å) where the scattering response was dominated by Porod 1/Q4 behavior typical of internal voids. This behavior was especially strong for the samples fabricated from the extruded polycrystal, but was also present in the as-received single crystal. The degradation of the single crystal Porod response after compressional cold working is in reasonable agreement with the calculated effect of flattening a spherical void.

The Effect of Grain Boundaries on Surface Diffusion Mediated-Planarization of Polycrystalline Cu Films

1995 ◽  
Vol 389 ◽  
Author(s):  
R.A. Brain ◽  
D.S. Gardner ◽  
D.B. Fraser ◽  
H.A. Atwater
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Surface Diffusion ◽  
Cross Sections ◽  
Boundary Surface ◽  
Surface Profile ◽  
Transmission Electron Micrograph ◽  
Cu Films ◽  
Transmission Electron

ABSTRACTIn situ, ultrahigh vacuum anneals were performed to induce Cu reflow at 500°C following deposition of Cu films and a Ta barrier layer on 1 μm wide by 1 μm deep trenches. Transmission electron micrograph cross-sections show profiles which suggest that grain boundaries and surface energy anisotropy significantly affect reflow. The extent of reflow is dependent on the structure of grain boundary-surface intersections, and the surface profile consists of regions of low curvature within grains and with sharp discontinuities in curvature at grain boundaries, a structure that inhibits surface diffusion. We present results showing how the surface diffusion mediated reflow varies with grain boundary groove angle and position, and compare these results with finite-element simulations that model surface diffusion-driven reflow.

The Influence of Grain Boundary Migration on the Diffusion Behaviour of Thin Films

1980 ◽  
Vol 35 (6) ◽  
pp. 613-618
Author(s):  
E. Ehrmann-Falkenau ◽  
A. Wagendristel
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Boundary Surface ◽  
Depth Profiling ◽  
Lattice Diffusion ◽  
Grain Boundary Migration ◽  
Order Of Magnitude ◽  
Diffusion Behaviour

Simultaneous grain boundary-, surface- and lattice diffusion in hypothetical thin film couples of miscible components was computer simulated. On this basis the diffusion into fixed and moving grain boundaries is discussed with respect to the determination of diffusivities by depth profiling methods. The data evaluated from the synthesised depth profiles according to Whipple-Le Claire as well as to Gilmer and Farrell were compared with the diffusivities used for the computation. Agreement was found for systems with a fixed grain boundary network. Moving grain boundaries, however, may cause errors of an order of magnitude towards lower grain boundary diffusivities

scholarly journals Increasing contribution of grain boundary compliance to polycrystalline ice elasticity as temperature increases

2018 ◽  
Vol 64 (246) ◽  
pp. 669-674
Author(s):  
COLIN M. SAYERS
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Orientation Distribution ◽  
Resonant Ultrasound Spectroscopy ◽  
Wave Velocities ◽  
Polycrystalline Ice ◽  
Resonant Ultrasound ◽  
Increasing Temperature ◽  
Shear Compliance

ABSTRACTMeasured elastic stiffnesses of ice polycrystals decrease with increasing temperature due to a decrease in grain boundary stiffness with increasing temperature. In this paper, we represent grain boundaries as imperfectly bonded interfaces, across which traction is continuous, but displacement may be discontinuous. We express the additional compliance due to grain boundaries in terms of a second-rank and a fourth-rank tensor, which quantify the effect on elastic wave velocities of the orientation distribution as well as the normal and shear compliances of the grain boundaries. Measurement of the elastic stiffnesses allows determination of the components of these tensors. Application of the method to resonant ultrasound spectroscopy measurements made on ice polycrystals enables determination of the ratio BN/BS of the normal to shear compliance of the grain boundaries, which are found to be more compliant in shear than in compression. The ratio BN/BS is small at low temperatures, but increases as temperature increases, implying that the normal compliance increases relative to the shear compliance as temperature increases.

Effects of cold working degrees on grain boundary characters and strain concentration at grain boundaries in Alloy 600

2011 ◽  
Vol 53 (3) ◽  
pp. 1137-1142 ◽  
Author(s):  
J. Hou ◽  
Q.J. Peng ◽  
Z.P. Lu ◽  
T. Shoji ◽  
J.Q. Wang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cold Working ◽  
Alloy 600 ◽  
Strain Concentration

A Highly Reliable Al Line with Controlled Texture and Grain Boundaries

1995 ◽  
Vol 391 ◽  
Author(s):  
M. Hasunuma ◽  
H. Toyoda ◽  
T. Kawanoue ◽  
S. Ito ◽  
H. Kaneko ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Empirical Relation ◽  
Boundary Structure ◽  
Homogeneous Microstructure ◽  
Grain Boundary Structure ◽  
Dislocation Arrays ◽  
Order Of Magnitude ◽  
Individual Grains

AbstractIn order to clarify the relationship between Al line reliability and film microstructure, especially grain boundary structure and crystal texture, we have tested three kinds of highly textured Al lines, namely, single-crystal Al line, quasi-single-crystal Al line and hypertextured Al line, and two kinds of conventional Al lines deposited on TiN/Ti and on SiO2. Consequently, the empirical relation between the electromigration (EM) lifetime of Al line † and the (111) full width at half maximum (FWHM) value ω is described by † ∝ ω-2 [1]. This improvement of Al line reliability results from as following reasons; firstly, homogeneous microstructure and high activation energy of 1.28eV for the single-crystal Al line (ω=0.18°); secondly, sub-grain boundaries which consisted of dislocation arrays found in the quasi-single-crystal Al line (ω=0.26°) has turned out to be no more effective mass transport paths because dislocation lines are perpendicular to the direction of electron wind. Although there exist plural grain boundary diffusion paths in the newly developed hypertextured Al line (ω=0.5°) formed by using an amorphous Ta-Al underlayer {1], the vacancy flux along the line has been suppressed to the same order of magnitude of single crystal line. It has been clarified that the decrease of FWHM value has promoted the formation of sub-grain boundaries and low-angle boundaries with detailed orientation analysis of individual grains in the hypertextured film. The longer EM lifetime for the hypertextured Al line is considered to be due to the small grain boundary diffusivities for these stable grain boundaries, and this diffusivity reduction resulted in the suppression of void/hillock pair in the Al lines. These results have confirmed that controlling texture and/or grain boundary itself is a promising approach to develop reliable Al lines which withstand higher current densities required in future ULSIs.

A Practical Method of Determining Grain Boundary Crystallographic Parameters Using Microdiffraction

1985 ◽  
Vol 43 ◽  
pp. 250-251
Author(s):  
Valerie Randle ◽  
Brian Ralph
Keyword(s):  
Electron Diffraction ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Theoretical Models ◽  
Practical Method ◽  
Precise Determination ◽  
Bright Field Image ◽  
Bright Field ◽  
Carbide Particles

To relate the observed structures in grain boundaries to the theoretical models requires a knowledge of the main parameters describing the crystallography across the boundary (e.g. 1). A number of methods have been described for determining the axis/angle of misorientation, ℓ/Θ and the plane of the boundary using conventional electron diffraction SADP (e.g. 2-3). In a recent study a distinction between the migration characteristics of special and general boundaries was made (4). A precise determination of the boundary parameters requires the manipulation of data from Kikuchi patterns (e.g. 3) and, in SADP these are only excited from thicker portions of the foil.Microdiffraction has a number of significant advantages for such studies (e.g. 5) as demonstrated here. The results come from a major investigation of the interaction between precipitate dispersions and grain boundaries (6). The alloy chosen is Nimonic PE 16 (the heat treatments are given in the figure captions). Figure 1 is a bright field image of a low angle grain boundary pinned by carbide particles.

SEM-ECP Analysis of Grain-Boundary Character Distribution in Polycrystalline Materials

1996 ◽  
Vol 54 ◽  
pp. 354-355
Author(s):  
Tadao Watanabe
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Polycrystalline Materials ◽  
Grain Boundary Character Distribution ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution

As demonstrated early 1980’s (1), the scanning electron rnicrocopy-electron channelling pattern (SEM-ECP) technique is very powerful in determination of orientation of individual grains and the character of grain boundaries in polycrystalline materials. Figure 1(a) and (b) show SEM and ECP images of a grain boundary in polycrystal line iron-6.5 mass % silicon ribbon produced by rapid solidification and subsequent annealing. We can intuitively recognize from the SEM-ECP image that the character of the boundary is of <100> tilt type with about 7° misorientation angle. This kind of direct observation is very useful for a study of grain boundary migration and grain growth.This paper discusses advantages of the SEM-ECP technique for the precise determination of the character of grain boundary and for statistical analysis of grain boundaries to bridge roles of individual grain boundaries and bulk properties in a polycrystal. The new microstructural parameter associated with grin boundary termed “grain boundary character distribution (GBCD)” which was introduced by the present author (2,3) and has been utilized in designing and engineering grain boundaries in order to produce desirable and/or high bulk performance in polycrystalline materials (4,5). GBCD describes the type and the frequency of different types of grain boundaries, ie. random general boundaries and special boundaries like low-angle boundaries and low Σ coincidence boundaries.

On {h,1,1}, the Recrystallisation Texture of Heavily Cold Rolled BCC Steel

2004 ◽  
Vol 467-470 ◽  
pp. 269-274 ◽  
Author(s):  
Hotaka Homma ◽  
Shuichi Nakamura ◽  
Naoki Yoshinaga
Keyword(s):  
Grain Boundary ◽  
Cold Rolling ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Rolling Direction ◽  
Experimental Results ◽  
Rolled Steel ◽  
Fibre Structure ◽  
Pole Figures ◽  
Cold Rolled

Heavily cold rolled BCC steel has been indicated to generate {411}<148> recrystallisation texture and its family orientations which might be represented as {h,1,1}<1/h,1,2>. As a-fibre structure, or RD//<011> texture is significantly developed during the cold rolling, it is naturally speculated to be the recrystallisation site of {h,1,1}<1/h,1,2> fibre. The present paper prompts to demonstrate the recrystallisation procedure by utilising EBSP-OIM analysis. The first demonstration was carried out with OIM analysis on partially recrystallised cold rolled steel. At the stage of 50% recrystallisation, only ND//<111> texture has appeared for the recrystallised area. {100}<011> - {211}<011> a-fibre remains as deformed structure, and several {h,1,1}<1/h,1,2> grains could be found at the grain boundaries. Therefore, a bi-crystal of {100}<011> was employed to simulate the irregular deformation at the grain boundary. After cold rolling, a warp toward the grain boundary was observed. Although the interior of the {100}<011> single crystal was hardly recrystallised, sharp {411}<148> texture was created along the grain boundary. In order to confirm the phenomenon, another experiment was carried out that a cold rolled {100}<011> single crystal was bent along the rolling direction and annealed. Very sharp {411}<148> recrystallisation texture was formed again at the bent perimeter. These experimental results lead us to conclude that the irregular strain was sufficiently piled at the grain boundary after the heavy deformation and generates {h,1,1}<1/h,1,2> texture. On {100} pole figures, the recrystallisation textures were equivalently scattered around three <100> poles, therefore the rotation relationship around <111> axes with the original orientation was suggested.

Annealing Texture in a Rolled and Artificially Nucleated Aluminum Single Crystal

1958 ◽  
Vol 2 ◽  
pp. 7-22
Author(s):  
S. Kohara ◽  
M. N. Parthasarathi ◽  
Paul A. Beck
Keyword(s):  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Pure Aluminum ◽  
Boundary Edge ◽  
Orientation Relationships ◽  
Aluminum Single Crystal ◽  
Self Diffusion ◽  
Large Numbers ◽  
The Matrix

AbstractIt has been suggested that the experimentally observed orientation dependence of the mobility of grain boundaries in f.c.c. metals may be related to the dependence of the rate of self diffusion in grain boundaries on the disorientation across the boundary. Later, this relative orientation effect on the rate of boundary diffusion and self diffusion was experimentally observed. It was shown by Hoffman and Turnbull that in bicrystals of silver misoricnted around (100) by 9° to 28°, self diffusion along the boundary (parallel to the common (100)) may be described in terms of a coefficient of self diffusion in individual grain boundary edge dislocation pipes, orders of magnitude larger than the coefficient of lattice self diffusion. It is significant that the coefficient of self diffusion in grain boundary dislocation pipes was found to be independent of the misorientation (i.e., of the density of edge dislocations in the boundary) at least up to 28°, suggesting that even a boundary of such a great misorientation may be considered as a network of dislocations, as far as self diffusion is concerned.In recent experiments the relative mobilities of boundaries in various orientations between a deformed (99.98% pure) aluminum single crystal and recrystallized grains growing in it in fairly well defined, lattice orientation relationships were compared. The matrix crystal was rolled to 80% R.A. on a (110) plane in a [112] direction, after which the strip still retained its initial orientation and the texture was very sharp. Recrystallized grains quite accurately oriented so as to have highest overall boundary mobility, i.e., corresponding to 40° rotations around the two 111 axes of the matrix grain lying in the rolling plane, were produced in large numbers by random nucleation on one side of the strip (rubbing one side with sandpaper and annealing). The re crystallized grains, that were at first growing in very large numbers and quite randomly but only in the thin surface layer highly deformed by abrasion (nucleation side), on annealing for 600 sec at 350°C grew across the whole thickness (0,010″) of the rolled single crystal. As a result of very selective growth, the recrystallized grains reaching the other side of the strip (growth side) showed a very sharp texture consisting of four components with the orientations described.

Analysis of defect formation in Nb-doped SrTiO3 by impedance spectroscopy

2001 ◽  
Vol 16 (1) ◽  
pp. 192-196 ◽  
Author(s):  
Seong-Ho Kim ◽  
Jung-Ho Moon ◽  
Jae-Hwan Park ◽  
Jae-Gwan Park ◽  
Yoonho Kim
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Thermal Activation ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
Activation Energies ◽  
Single Grain

The thermal activation energies for conduction of Nb-doped SrTiO3 grains and grain boundaries have been investigated by impedance spectroscopy. First, to observe the effect of electrode/SrTiO3 bulk interface, the varied impedances of SrTiO3 single crystal were measured with temperatures. The activation energy of an electrode/bulk interface was determined to be 1.3 eV, whereas that of bulk was 0.8 eV. When the impedances of Nb-doped SrTiO3 ceramics were measured, it was suggested that the more precise impedance values of a single grain and a single grain to grain junction be obtained using a microelectrode method. The activation energies for a grain, a grain boundary, and an electrode/bulk interface were determined to be about 0.8, 1.3, and 1.5 eV, respectively. From these measured results, it was suggested that the activation energy, 0.8 eV, measured in grain was originated from oxygen vacancies and the activation energy, 1.3 eV, in grain boundary was from strontium vacancies.

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