Interfacial structure of grain boundary α allotriomorphs in a hypoeutectoid TiCr alloy

1988 ◽  
Vol 22 (9) ◽  
pp. 1509-1514 ◽  
Author(s):  
T. Furuhara ◽  
A.M. Dalley ◽  
H.I. Aaronson
Keyword(s):  
Grain Boundary ◽  
Interfacial Structure

The interfacial structure of orthogonally oriented twins in YBa2Cu3O7

1993 ◽  
Vol 51 ◽  
pp. 938-939
Author(s):  
Yimei Zhu ◽  
M. Suenaga ◽  
J. Tafto
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Twin Boundary ◽  
Current Density ◽  
Interfacial Structure ◽  
Hrem Image ◽  
Twin Boundaries ◽  
Wedge Shape

Interfaces such as the twin boundary and grain boundary in YBa2Cu3O7-δ are thought to be important in reconciling the large discrepancy between the low critical-current density observed in bulk polycrystalline. Recently, we studied another type of frequently encountered interface, i.e., the interface between the orthogonally orientated (110) and (-110) twins. In the vicinity of the interface, the crystal has a characteristic geometry because of additional constrains due to the impediment and the local orientational difference. The impinging twins usually have a wedge shape (Fig. la), and when the wedge slope is large, the tip of the twin splits (Fig. lb). A HREM image of a tapered twin is shown in Fig.2. Four twin variants give rise to five boundaries. Boundaries between IV-III, III-IV, IV-II, and II-IV are twin boundaries, while II-III, which has no apparent structure, is the interface of the orthogonal twins. If there is no constrain, the orientation of II and III should be equivalent (Fig.3a and 3b); however, we observed that the lattice in II does not align with that in III.

scholarly journals On the Effect of Local Grain-Boundary Chemistry on the Macroscopic Mechanical Properties of a High Purity Y2O3-Al2O3-Containing Silicon Nitride Ceramic

2004 ◽  
Vol 839 ◽  
Author(s):  
A. Ziegler ◽  
J.M. McNaney ◽  
M. J. Hoffmann ◽  
R. O. Ritchie
Keyword(s):  
Mechanical Properties ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Oxygen Content ◽  
High Purity ◽  
Interfacial Structure ◽  
Crack Advance ◽  
Transgranular Fracture ◽  
Boundary Films ◽  
Boundary Chemistry

ABSTRACTThe effects of grain-boundary chemistry on the mechanical properties of a high-purity silicon nitride ceramics were investigated, with specific emphasis on the role of oxygen. Variations in the grain-boundary oxygen content, through control of oxidizing heat treatments and sintering additives, was found to result in a transition in fracture mechanism from transgranular to intergranular fracture, with an associated increase in fracture toughness. This phenomenon is correlated to an oxygen-induced change in grain-boundary chemistry that appears to affect fracture by “weakening” the interface, facilitating debonding and crack advance along the boundaries, thereby enhancing the toughness by grain bridging. It is concluded that if the oxygen content in the thin grain-boundary films exceeds a lower limit, which is ∼0.87 equiv% oxygen content, then the interfacial structure and bonding characteristics favor intergranular debonding during crack propagation; otherwise, transgranular fracture ensues, with consequent low toughness.

Extension of HRTEM Resolution: Solving Structures of Grain Boundary and Interface Using Gerchberg-Saxton Algorithm and Blind Deconvolution

2001 ◽  
Vol 7 (S2) ◽  
pp. 242-243
Author(s):  
F.-R. Chen ◽  
H. Ichinose ◽  
J. J. Kai ◽  
L. Chang
Keyword(s):  
Grain Boundary ◽  
High Frequency ◽  
Blind Deconvolution ◽  
Structural Information ◽  
Degree Of Freedom ◽  
Interfacial Structure ◽  
Lens System ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Simulated Images

Oxides, nitrides, carbides and silicides contain more than one type of atoms that gives one extra degree of freedom in the grain boundary and interfacial structure. This degree of freedom is the choice of the boundary plane containing different type of atoms which results of several structural multiplicities in the boundary. Coexistence of the structural multiplicities (or boundary domains) in the interface and grain boundary were reported [1, 2]. The structural information in high frequency domain is usually blurred and lost in the lens system of a high resolution transmission electron microscopes (HRTEM) such that the HRTEM image may not truly represent the real structure. Conventionally, the structures of grain boundary and interface were solved using forward method. The forward method involves matching the simulated images from guessed possible models with the through focal series experimental images. Recently, rereconstruction methods such as focal variation holography [3, 4], tiltbeam holography [5] and Gerchberg-Saxton algorithm [6] provide a backward (direct) way to recover the structural information lost in a modern microscope.

scholarly journals Effects of Anisotropy and In-Plane Grain Boundary in Cu/Pd Multilayered Films with Cube-on-Cube and Twinned Interface

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Xiang Chen ◽  
Shayuan Weng ◽  
Xing Yue ◽  
Tao Fu ◽  
Xianghe Peng
Keyword(s):  
Mechanical Properties ◽  
Grain Boundary ◽  
Multilayer Film ◽  
Polycrystalline Sample ◽  
Interfacial Structure ◽  
Necessary Condition ◽  
Strengthening Effect ◽  
Multilayered Films ◽  
Crystalline Materials ◽  
Dynamics Simulations

AbstractIn crystalline materials, grain boundary and anisotropy of crystal structure affect their mechanical properties. The effects of interfacial structure on the mechanical properties may be diverse when the multilayer film is loaded along different directions. In this work, we performed a series of molecular dynamics simulations of the tension of in-plane single and polycrystalline Cu/Pd multilayered films with cube-on-cube (COC) and twinned interfaces to explore the effects of the interfacial structure, loading direction and in-plane grain boundaries on their mechanical properties. The interfacial misfit dislocation lines become bent after relaxation, and the high temperature of 300 K was found as a necessary condition. When stretched along 〈110〉 direction, the strengthening effect of the COC interface is more noticeable; however, when stretched along 〈112〉 direction, the twin interface's strengthening effect is more visible, showing the anisotropic effect of interfacial structure on mechanical properties. However, in the in-plane honeycomb polycrystalline sample, the twin interface showed a pronounced strengthening effect, and no jogged dislocations were observed.

Evidence by Hrem of Interfacial Modification Induced by Equilibrium Segregation in GE(S) Bicrystal

1993 ◽  
Vol 319 ◽  
Author(s):  
A. Charai ◽  
J.L. Rouviere
Keyword(s):  
Grain Boundary ◽  
Radioactive Tracer ◽  
Hydrogen Atmosphere ◽  
Interfacial Structure ◽  
Energy Structure ◽  
Sulfur Segregation ◽  
Experimental Conditions ◽  
Interfacial Modification ◽  
Electron Energy Loss ◽  
Equilibrium Segregation

AbstractThe structure of a [001] tilt grain boundary Σ=25(710) in germanium was investigated by HREM as prepared and after sulfur segregation. The characterisation of Ge(S) system was performed using techniques such as Auger Electron Spectroscopy, Electron Energy Loss Spectroscopy and radioactive tracer analysis. Before the sulfur introduction, this grain boundary is usually sensitive to the preferential etching during the TEM sample preparation which makes the observation difficult. This effect, depending on experimental conditions, can either partially or completely disappear. The interfacial structure as prepared and after annealing under argon or under hydrogen atmosphere can be described as a stacking of several structures with different energies. After sulfur segregation no preferential etching is observed because the lowest energy structure of the as prepared grain boundary is stabilized. The tilt angle and the plane of the grain boundary remain constant.

Evidence for the Presence of a Twist-Grain-Boundary Structure in Confined Hybrid Non-Chiral Smectic Liquid Crystal Films

1998 ◽  
Vol 543 ◽  
Author(s):  
Y. Hu ◽  
L. J. Martinez-Miranda
Keyword(s):  
Liquid Crystal ◽  
Grain Boundary ◽  
Grazing Incidence ◽  
Interfacial Structure ◽  
Boundary Structure ◽  
Liquid Crystal Films ◽  
Smectic Liquid Crystal ◽  
X Ray Scattering ◽  
Grain Boundary Structure ◽  
Crystal Films

AbstractWe have used Grazing Incidence X-ray Scattering to study the depth dependence of the interfacial structure of smectic liquid crystal (8CB) hybrid films. These films are bounded by a grated glass substrate and air, and have been studied as a function of both temperature and thickness. Our measurements indicate the presence of both a chevron structure and a structure similar to the helical twist-grain-boundary (TGB) phase. Our measurements constitute the first to show that this structure can also be observed in hybrid smectic liquid crystal films. The twisted structure is the result of anchoring at two dissimilar competing confining surfaces.

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