The Role of Transmission Electron Microscopy in Characterizing the Nature and Behavior of Grain Boundaries

1971 ◽  
Vol 29 ◽  
pp. 102-103
Author(s):  
L. E. Murr
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Degrees Of Freedom ◽  
Effective Means ◽  
Average Energy ◽  
Interfacial Free Energy ◽  
Transmission Electron ◽  
And Behavior

Grain boundaries represent the single, most dominant imperfection in structural materials of engineering and industrial importance, and are a controlling factor in the strength of materials. Transmission electron microscopy, combined with the ability to gain direct crystallographic information from associated selected-area electron diffraction patterns, represents perhaps the most effective means for the investigation of the nature and behavior of grain boundaries in solids.Any segment of a grain boundary has associated with it five degrees of freedom. The electron microscope has the capability to characterize these degrees of freedom and to uniquely define the geometrical and crystallographic nature of a grain boundary. In addition, once the true geometry of intersecting grain boundaries or grain boundaries intersecting with other interfaces is determined, interfacial free energy ratios can be calculated from which the average energy associated with particular types of interfaces can be determined.

The Effects of Interfacial Torque on the Geometry of Twin-Grain Boundary Intersections

1971 ◽  
Vol 29 ◽  
pp. 220-221
Author(s):  
R. J. Horylev ◽  
L. E. Murr
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Grain Boundary ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Interfacial Free Energy ◽  
Boundary Misorientation ◽  
Transmission Electron ◽  
Boundary Intersections

The characterization of a grain boundary in a thin film section by transmission electron microscopy has been described previously. In addition, the geometrical configurations resulting from interfacial torque at twin-grain boundary intersections have been described by the use of the electron microscope. There have been, however, no attempts to systematically study the effect of interfacial torque on the geometry of twin-grain boundary intersections in thin metal films. Neither have there been any attempts to systematically study the interrelationships of the degrees of freedom characterizing a grain boundary in a three-dimensional thin section in the electron microscope. The present work describes the relationship of grain boundary misorientation , inclination (θ), and asymmetry (Φ) to relative interfacial free energy; and the dependence of these parameters on relative interfacial torque at twin-grain boundary intersections observed by transmission electron microscopy.

Grain-Boundary Segregation and Phase-Separation Mechanism in Yttria-Stabilized Tetragonal Zirconia Polycrystal

2011 ◽  
Vol 484 ◽  
pp. 82-88
Author(s):  
Koji Matsui ◽  
Hidehiro Yoshida ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Cubic Phase ◽  
Phase Boundaries ◽  
Transmission Electron ◽  
Sintering Condition

Microstructure development during sintering in 3 mol% Y2O3-stabilized tetragonal ZrO2 polycrystal (Y-TZP) was systematically investigated in two sintering conditions: (a) 1100-1650°C for 2 h and (b) 1300°C for 0-50 h. In the sintering condition (a), the density and grain size in Y-TZP increased with the increasing sintering temperature. Scanning transmission electron microscopy (STEM) and nanoprobe X-ray energy dispersive spectroscopy (EDS) measurements revealed that the Y3+ ion distribution was nearly homogeneous up to 1300°C, i.e., most of grains were the tetragonal phase, but cubic-phase regions with high Y3+ ion concentration were clearly formed in grain interiors adjacent to the grain boundaries at 1500°C. High-resolution transmission electron microscopy (HRTEM) and nanoprobe EDS measurements revealed that no amorphous or second phase is present along the grain-boundary faces, and Y3+ ions segregated not only along the tetragonal-tetragonal phase boundaries but also along tetragonal-cubic phase boundaries over a width below about 10 nm, respectively. These results indicate that the cubic-phase regions are formed from the grain boundaries and/or the multiple junctions in which Y3+ ions segregated. We termed this process a “grain boundary segregation-induced phase transformation (GBSIPT)” mechanism. In the sintering condition (b), the density was low and the grain-growth rate was much slow. In the specimen sintered at 1300°C for 50 h, the cubic-phase regions were clearly formed in the grain interiors adjacent to the grain boundaries. This behavior shows that the cubic-phase regions were formed without grain growth, which can be explained by the GBSIPT model.

Grain Boundary Transformations in Bi-Doped Copper

1991 ◽  
Vol 238 ◽  
Author(s):  
Elsie C. Urdaneta ◽  
David E. Luzzi ◽  
Charles J. McMahon
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Treatment Time ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron

ABSTRACTBismuth-induced grain boundary faceting in Cu-12 at ppm Bi polycrystals was studied using transmission electron microscopy (TEM). The population of faceted grain boundaries in samples aged at 600°C was observed to increase with heat treatment time from 15min to 24h; aging for 72h resulted in de-faceting, presumably due to loss of Bi from the specimen. The majority of completely faceted boundaries were found between grains with misorientation Σ=3. About 65% of the facets of these boundaries were found to lie parallel to crystal plane pairs of the type {111}1/{111]2- The significance of these findings in light of recent high resolution electron microscopy experiments is discussed.

Structural analysis of faceted grain boundaries in Bi-doped Cu

1989 ◽  
Vol 47 ◽  
pp. 278-279
Author(s):  
D. E. Luzzi ◽  
B. Blum ◽  
H. Inui
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Transformation ◽  
Structural Analysis ◽  
Grain Boundaries ◽  
Degrees Of Freedom ◽  
Pattern Analysis ◽  
Two Dimensional ◽  
Kikuchi Pattern ◽  
Transmission Electron

Conventional(CTEM)and high-resoIution(HREM) transmission electron microscopy have been used to investigate the structure of faceted grain boundaries in Cu doped with Bi. The solubility of Bi in Cu exhibits retrograde behavior with a maximum of 160 at. ppm. at 850 ° C and decreasing above and below this temperature (eg. to < 3 at. ppm. at 600 ° C). When aged at temperatures below this retrograde region, Blis known to segregate tothe grain boundaries. In addition to this segregation, these materials exhibit a reversible faceting-de-faceting transition at 710 ° C which has been postulated asarising from a two-dimensional phase transformation at the grain boundaries. Until the present time, little experimental work has been doneto characterize the structures of these faceted boundaries.In the present experiments, Kikuchi pattern analysis and edge-on imaging have been used to characterize the five macroscopic degrees of freedom of individual facets. Bulk Cu specimens with 50 at.ppm.

In-Plane Grain Boundary Effects on the Transport Properties of La0.7Sr0.3MnO3-δ Thin Films

1997 ◽  
Vol 494 ◽  
Author(s):  
J. Y. Gu ◽  
S. B. Ogale ◽  
K. Ghosh ◽  
T. Venkatesan ◽  
R. Ramesh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Effects ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Low Field ◽  
Grain Structures ◽  
Transmission Electron

ABSTRACTC-axis oriented La0.7Sr0.3MnO3.δ (LSMO) films were fabricated on the top of SrTiO3/YBa2Cu3O7 grown on MgO(001) substrates. From x-ray φ-scan and planar transmission electron microscopy measurements, the LSMO layer in the LSMO/SrTiO3/YBa2Cu3O7/MgO heterostructure is found to have coherent in-plane grain boundaries with a predominance of 45° rotations (between [100] and [110] grains) in addition to the cube-on-cube epitaxial relationship. Also, epitaxial LSMO/Bi4Ti3O12/LaAl03 (001) and c-axis textured LSMO/Bi4Ti3O12/SiO2/Si(001) with random in-plane grain boundaries are introduced as the counterparts for comparison. The resistivity and magnetoresistance (MR) of LSMO layer were measured and compared in these three different heterostructures. The low field MR at low temperature shows a dramatic dependence on the nature of the grain boundary. An attempt is made to interpret these results on the basis of correlation between the magnetic properties and grain structures.

Structure of the ∑=3 (111) Grain Boundary in Cu-1.5%Sb

1992 ◽  
Vol 295 ◽  
Author(s):  
Richard W. Fonda ◽  
David E. Luzzi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Auger Electron ◽  
Preliminary Investigation ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron

AbstractGrain boundaries in quenched and aged Cu-i.5%Sb were examined with Auger electron microscopy, transmission electron microscopy, and high resolution electron microscopy. The ∑=3 grain boundaries are strongly faceted, with the facets lying primarily along the coincident (111) planes of the two grains. The grain boundaries are enriched in antimony, as demonstrated by both AES and HREM. HREM images of the ∑=3 (111) ║ (111) grain boundary differ from those of the Cu-Bi ∑ =3 (111) ║ (111) grain boundary in the lack of a significant grain boundary expansion to accommodate the excess solute at the boundary. A preliminary investigation of the atomic structure of the ∑=3 (111) ║ (111) facet by HREM and multislice calculations is presented.

Grain boundary character information via individual imaging or statistical analyses: complexion transitions and grain boundary segregation

2021 ◽  
Author(s):  
Katharina Marquardt ◽  
David Dobson ◽  
Simon Hunt ◽  
Ulrich Faul
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Bulk Viscosity ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Transmission Electron

&lt;p&gt;Grain boundaries affect bulk properties of polycrystalline materials, such as electrical conductivity, melting or bulk viscosity. In the past two decades, observations of marked bulk material property changes have been associated with changes in the structure and composition of grain boundaries. This led to the term &amp;#8220;grain boundary complexions&amp;#8221; to mark the phase-like behaviour of grain boundaries while differing from phases in the sense of Gibbs (Cantwell 2014).&lt;/p&gt;&lt;p&gt;Here we introduce the principles of grain boundary structure to property relations and potent methods to study these. The focus is on the combination of structural, chemical and statistical analysis as obtainable using transmission electron microscopy and electron backscatter diffraction. Data from these complementary methods will be discussed on two systems; garnet and olivine polycrystals.&lt;/p&gt;&lt;p&gt;Past elasticity measurements showed that the Youngs modulus of garnet polycrystals changes as a function of sintering pressure (Hunt et al. 2016). Here we used high resolution transmission electron microscopy to study the structure of grain boundaries from polycrystals synthesized at low (4-8 GPa) and high (8-15) GPa sintering pressure. The HRTEM data were acquired using an image-corrected JEOL ARM 300 to achieve the highest resolution at low electron doses using a OneView camera. Our data indicate a grain boundary structural change occurs from &amp;#8220;low-pressure&amp;#8221; to &amp;#8220;high pressure&amp;#8221; grain boundaries, where the grain boundary facets change from &gt;100 nm &amp;#8211; 20 nm to 3-7 nm length scale, respectively. We conclude that sintering pressure affects grain-boundary strength and we will evaluate how this may influence anelastic energy loss of seismic waves through elastic or diffusional accommodation of grain-boundary sliding.&lt;/p&gt;&lt;p&gt;Polycrystalline olivine samples show different viscosity related to grain boundary segregation of impurities. To investigate if the distribution of grain boundaries is affected by grain boundary chemistry, we analysed grain orientation data from over 4x10&lt;sup&gt;4&lt;/sup&gt; grains, corresponding to more than 6000 mm grain boundary length per sample. Using stereology, we extract the geometry of the interfacial network. The thus obtained grain boundary character distribution (GBCD) is discussed in relation to bulk viscosity.&lt;/p&gt;

The Characterization of a Grain Boundary by Transmission Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 436-437 ◽  
Author(s):  
R.J. Horylev ◽  
L.E. Murr
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Degrees Of Freedom ◽  
Boundary Plane ◽  
The Other ◽  
Two Degrees Of Freedom ◽  
Transmission Electron ◽  
Three Degrees Of Freedom

Read has shown that an arbitrary grain boundary has five degrees of freedom associated with it. Three degrees of freedom are necessary to describe the orientation of one grain with respect to the other, while the remaining two degrees of freedom position the boundary plane between the adjacent grains.Figure 1(a) depicts a general twin boundary-grain boundary intersection. The degrees of freedom for the grain boundary are represented by (HKL)1, (HKL)2, Θ, θGB, ø. Two degrees of freedom are contained in the surface orientations of the grains.

Dislocation - Grain Boundary Interaction in Nickel Bicrystals Evolution of the Resulting Defects under Thermal Treatment

2000 ◽  
Vol 652 ◽  
Author(s):  
Louisette Priester ◽  
Sophie Poulat ◽  
Brigitte Décamps ◽  
Jany Thibault
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Thermal Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Dislocation Network ◽  
Boundary Interaction ◽  
Transmission Electron

ABSTRACTThe interactions between lattice dislocations and grain boundaries were studied in nickel bicrystals. Three types of grain boundaries, according to their energy, were investigated : singular σ3 {111}, vicinal near σ11 {311} and general near σ11 {332} grain boundaries. The experiments were performed by transmission electron microscopy using a set of techniques : conventional, weak beam, in situ and high resolution transmission electron microscopy. Dislocation transmission from one crystal to the other was only observed for σ3 {111} GB. It consists in a decomposition within the grain boundary of the trapped lattice dislocation followed by the emission of one partial in the neighbouring crystal. A high resolved shear stress is required to promote the emission process. Most often, the absorbed lattice dislocations or extrinsic grain boundary dislocations react with the intrinsic dislocation network giving rise to complex configurations. The evolutions with time and upon thermal treatment of these configurations were followed by in situ transmission electron microscopy. The evolution processes, which differ with the type of grain boundaries, were analyzed by comparison with the existing models for extrinsic grain boundary dislocation accommodation. They were tentatively interpretated on the basis of the grain boundary atomic structures and defects obtained by high resolution transmission electron microscopy studies.

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