Periodic grain boundary structures in aluminium I. A combined experimental and theoretical investigation of coincidence grain boundary structure in aluminium

1977 ◽  
Vol 357 (1691) ◽  
pp. 453-470 ◽  
Keyword(s):  
Grain Boundary ◽  
Rigid Body ◽  
Interatomic Potential ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Annealing Twins ◽  
Theoretical Predictions ◽  
Atomic Relaxation ◽  
Pseudo Potential

The results of a computer simulation of the structure of periodic grain boundaries between twin related crystals of aluminium are described. An interatomic potential derived on the basis of pseudo-potential theory was used. The algorithm employed allows simultaneous local atomic relaxation and rigid body translation of the adjacent grains. It was found that rigid body translation is a dominant contribution to relaxation, and that the energy of a boundary, y, is not simply related to boundary periodicity. In addition, annealing twins in aluminium were observed by using transmission electron microscopy and detailed correspondence with theoretical predictions was found in two areas; the calculated y ’s of experimentally observed boundary planes were lower than those of geometrically possible alternatives, and excellent agreement between predicted and experimentally measured rigid body translations was obtained for two types of tilt boundary.

Observations and implications of grain boundary dislocation networks in high-angle YBa2Cu3O7−δ grain boundaries

1990 ◽  
Vol 5 (5) ◽  
pp. 919-928 ◽  
Author(s):  
S. E. Babcock ◽  
D. C. Larbalestier
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Boundary Structure ◽  
High Angle ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Regular Networks

Regular networks of localized grain boundary dislocations (GBDs) have been imaged by means of transmission electron microscopy in three different types of high-angle grain boundaries in YBa2Cu3O7-δ, implying that these boundaries possess ordered structures upon which a significant periodic strain field is superimposed. The occurrence of these GBD networks is shown to be consistent with the GBD/Structural Unit and Coincidence Site Lattice (CSL)/Near CSL descriptions for grain boundary structure. Thus, these dislocations appear to be intrinsic features of the boundary structure. The spacing of the observed GBDs ranged from ∼10 nm to ∼100 nm. These GBDs make the grain boundaries heterogeneous on a scale that approaches the coherence length and may contribute to their weak-link character by producing the “superconducting micro-bridge” microstructure which has been suggested on the basis of detailed electromagnetic measurements on similar samples.

Investigation of Grain Boundary Structure and Composition of Bismuth Embrittled Copper Bicrystals with Aberration-Corrected Scanning Transmission Electron Microscopy

2012 ◽  
Vol 18 (S2) ◽  
pp. 346-347
Author(s):  
C. Wade ◽  
M. McLean ◽  
R. Vinci ◽  
M. Watanabe ◽  
L. Giannuzzi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Scanning Transmission Electron Microscopy ◽  
Boundary Structure ◽  
Scanning Transmission Electron ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Aberration Corrected

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Brittle Grain Boundary Fracture in Iridium

1977 ◽  
Vol 35 ◽  
pp. 294-295
Author(s):  
D. L. Rohr ◽  
S. S. Hecker ◽  
L. E. Murr
Keyword(s):  
Grain Boundary ◽  
Nuclear Power ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Thin Foils ◽  
Transmission Electron ◽  
Grain Boundary Fracture ◽  
Space Nuclear Power ◽  
Boundary Fracture ◽  
Brittle Intergranular Fracture

Iridium is a most interesting fee metal with a high melting point (2443°C) and extremely high elastic moduli (Young's modulus of 76 million psi). Single crystals of Ir fail by brittle cleavage and polycrystalline Ir fails by brittle intergranular fracture at temperatures below 1000°C. We have previously shown that both modes of fracture are intrinsic and not impurity related. (1)The present study was undertaken to study the grain boundary structure of Ir by transmission electron microscopy. Sheet specimens of Ir-0.3%W (used in space nuclear power applications) were recrystallized at temperatures above 1300°C. Thin foils were prepared by spark planing and electropolishing with an acidified CaCl2 solution in a jet polisher and were examined in a JEOL 200 B electron microscope operated at 200 kv.We examined a large number of foils and found the most interesting grain boundary features to be ledges (2) (Fig. la).

TEM Studies of Grain Boundary Structure in a Cast Polycrystalline Silicon

2005 ◽  
Vol 475-479 ◽  
pp. 1673-1676 ◽  
Author(s):  
Isamu Kuchiwaki ◽  
Takahiro Hirabayashi ◽  
Hiroshi Fukushima
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Twin Boundary ◽  
Polycrystalline Silicon ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Resolution Electron ◽  
The Difference

Cast polycrystalline silicon for solar cell contains mostly straight twin boundaries which are thought to have little effect on the electrical activity. There are, however, some complicated grain boundaries in it. One of these boundaries consists of slightly curved and straight parts. The structure of this boundary was analyzed to investigate the difference of these two types of boundaries. The conventional transmission electron microscopy (TEM) found that this slightly curved boundary was the zigzag shaped boundary made by (11 _ ,2) and ( _ ,211) planes. High resolution electron microscopy (HREM) confirmed that (11 _ ,2) plane was the boundary of {112} Σ3 twin boundary which formed a straight grain boundary at the other end of the analyzed grain boundary, and also confirmed that ( _ ,2 11) plane was also the boundary of {112} Σ3 twin boundary which intersected with the former twin boundary at an angle of 120 [deg].

Effect of Sintering Additive Composition on Grain Boundary Structure in Liquid-Phase-Sintered Silicon Carbide

2007 ◽  
Vol 558-559 ◽  
pp. 897-902 ◽  
Author(s):  
Young Wook Kim ◽  
Je Hun Lee ◽  
Doh Yeon Kim
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Dominant Role ◽  
Boundary Structure ◽  
Dominant Factor ◽  
Sintering Additive ◽  
Sic Ceramics ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Sintered Silicon

Both the presence and absence of an amorphous intergranular film (IGF) between the SiC grains have previously been reported in liquid-phase-sintered SiC ceramics (LPS-SiC). The dominant factor(s) responsible for the grain boundary structure in LPS-SiC has not been clearly revealed. In the present study, LPS-SiC ceramics containing different compositions of sintering additives were fabricated and characterized with respect to their grain boundary structure, using both scanning and transmission electron microscopy. The results suggest that the sintering additive composition plays a dominant role in the evolution of grain boundary structure in LPS-SiC.

TEM Study of Secondary Grain Boundary Dislocations in Near-∑13, Near-∑17 and Near-∑29 [001] Twist Boundaries in Gold

1985 ◽  
Vol 43 ◽  
pp. 244-245
Author(s):  
S.E. Babcock
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Boundary Structure ◽  
Ordered Structure ◽  
Boundary Dislocation ◽  
High Angle ◽  
Extensive Search ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Twist Boundaries

In 1970, an extensive search by transmission electron microscopy (TEM) for evidence of ordered structure in high-angle [001] twist boundaries helped to establish the credibility of the DSC/CSL description of grain boundary structure. In this work, square grids of line contrast were found in boundaries for which the twist misorientation (Θ) was very near the special Σ5+ Σ13 and Σ17 Θ. The lines ran parallel to the primitive translation vectors (b(1) and b(2)) of the appropriate low-Σ DSC lattice, and their spacing correlated well with the spacing predicted by Frank's formula for dislocations with Burgers vectors b(1) and b(2). The images were interpreted as secondary grain boundary dislocation (SGBD) networks. Only for the near-Σ5 case was g•b analysis carried out to show that the line contrast was characteristic of b= 1/10 <310> type screw SGBD's.

Does Σ Control Intergranular Cracking in Ni3Al?

1990 ◽  
Vol 186 ◽  
Author(s):  
Hui Lin ◽  
David P. Pope
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Intergranular Fracture ◽  
Boundary Structure ◽  
Intergranular Cracking ◽  
Statistical Quality ◽  
Grain Boundary Character ◽  
Grain Boundary Structure ◽  
Theoretical Predictions

AbstractThe relation between intergranular fracture and grain boundary character was studied in Ni3Al using the electron backscattering pattern (EBSP) technique. Using specimens of small grain size, we are able to index the orientation of a large number of grains, thus improving the statistical quality of the data compared to previous results. Furthermore, we are able to characterize the boundary planes using the EBSP method because of the special specimen geometry used. It was found that Σ3 boundaries do have a substantially lower propensity for cracking as compared to other boundaries, but there is no correlation between grain boundary Σ value and the propensity for cracking for low Σ and low angle boundaries. These results are in general agreement with recent theoretical predictions of grain boundary structure.

First-Principles Studies on Grain Boundary Energies of [110] Tilt Grain Boundaries in Aluminum

2007 ◽  
Vol 561-565 ◽  
pp. 1837-1840 ◽  
Author(s):  
Y. Inoue ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
First Principles ◽  
Boundary Structure ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Tilt Grain Boundary

The grain boundary structure and its energy are necessary for the fundamental understanding of the physical properties of materials. In aluminum, three distinct atomic structures of a Σ9(221)[110] tilt grain boundary have been reported in previous studies using atomistic simulations and a high-resolution transmission electron microscopy (HRTEM). In this work, we studied the atomic structure and energy of the Σ9 tilt grain boundary in aluminum using first-principles calculations. A comparison of the grain boundary energies among the three distinct Σ9 tilt grain boundaries determined through first-principles calculations allowed us to identify the most stable atomic structure of Σ9 tilt grain boundary in aluminum.

Periodic grain boundary structures in aluminium. II. A geometrical method for analysing periodic grain boundary structure and some related transmission electron microscope observations

1977 ◽  
Vol 357 (1691) ◽  
pp. 471-483 ◽  
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Transmission Electron Microscope ◽  
Boundary Structure ◽  
Geometrical Method ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Line Defects

A crystallographic treatment is developed which clarifies the relation between the structure of a grain boundary and its location between relatively translated crystals. Characterization of line defects which can exist in grain boundaries is also facilitated by using this treatment, and the following topics are considered: (1) the computed structures in part I of this work; (2) steps at the cores of perfect grain boundary dislocations; (3) boundary structures related by c.s.l. symmetry; (4) partial grain boundary dislocations. Transmission electron microscope observations of topic 4 are presented.

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