Grain boundary wetting of different types of grain boundaries in the Cu–Ag system

The thin layers of a second phase (also called complexions) in grain boundaries (GB) and triple junctions (TJs) are more and more frequently observed in polycrystals. The prewetting (or premelting) phase transitions were the first phenomena proposed to explain their existence. The deficit of the wetting phase in case of complete wetting can also lead to the formation of thin GB and TJ phases. However, only the phenomenon of pseudopartial (or pseudoincomplete, or constrained complete) wetting permitted to explain, how the thin GB film can exist in the equilibrium with GB lenses of a second phase with non-zero contact angle.

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The Influence of Quenching Baths on Grain Boundary Wetting Transition in Sn–25 at% In alloy

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.273-276.649 ◽

2008 ◽

Vol 273-276 ◽

pp. 649-654

Author(s):

C.H. Yeh ◽

L.S. Chang ◽

Boris B. Straumal

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Liquid Nitrogen ◽

Liquid State ◽

Metallographic Analysis ◽

Wetting Transition ◽

X Ray Diffraction ◽

X Ray ◽

Saturated Water ◽

Grain Boundary Wetting

The wetting behavior of grain boundaries is affected by temperature, pressure and misorientation of grain boundaries. However, the influence of quenching baths on liquid state grain boundary wetting is rarely reported. In this work, this effect in the Sn−25 at% In alloy was investigated. The Sn−In alloy was prepared by smelting of In and Sn at 300°C for 6 hr in Ar atmosphere. Samples were annealed at temperature between 130 and 165°C and quenched in two kinds of baths: −10°C salt-saturated water and liquid nitrogen. The results from X-ray diffraction show a difference in preferential orientations between samples quenched in these two baths. Metallographic analysis reveals that the percentage of grain boundaries fully wetted in samples quenched in −10°C salt-saturated water is lower than that quenched in liquid nitrogen. It is pointed out that a proper quenching bath is necessary for preserving the initial microstructure of grain boundary wetting.

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TRANSPORT PROPERTIES OF JOSEPHSON JUNCTIONS AND SQUIDS EMPLOYING DIFFERENT TYPES OF YBCO GRAIN BOUNDARIES OBTAINED THROUGH THE BIEPITAXIAL TECHNIQUE

International Journal of Modern Physics B ◽

10.1142/s0217979200003332 ◽

2000 ◽

Vol 14 (25n27) ◽

pp. 3074-3079 ◽

Cited By ~ 2

Author(s):

F. CARILLO ◽

F. LOMBARDI ◽

F. MILETTO GRANOZIO ◽

V. PUNZO ◽

F. RICCI ◽

...

Keyword(s):

Magnetic Field ◽

Grain Boundary ◽

Grain Boundaries ◽

Experimental Evidence ◽

Transport Properties ◽

Circuit Design ◽

Quantum Interference ◽

Superconducting Quantum Interference Devices ◽

Different Types ◽

Seed Layers

Concepts and experimental procedures to obtain different types of YBa 2 Cu 3 O 7 grain boundaries Josephson junction through the biepitaxial technique have been developed. Various seed layers (MgO, CeO 2 and SrTiO 3) and substrates (MgO, SrTiO 3) have been used providing, for the biepitaxial technique, additional flexibility in circuit design. A detailed investigation on transport properties evidenced good performances for both junctions and superconducting quantum interference devices. Experimental evidence is given of a conventional magnetic field behavior in 45° tilt Artificial Grain Boundary (AGB) for which no π-loops are predicted along the interface.

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GRAIN BOUNDARY WETTING AND SOLIDIFICATION OF CONSTITUTIONAL LIQUID IN AZ91 MG CAST ALLOY

International Journal of Modern Physics B ◽

10.1142/s0217979210064745 ◽

2010 ◽

Vol 24 (15n16) ◽

pp. 2249-2254 ◽

Cited By ~ 1

Author(s):

TIANPING ZHU ◽

ZHAN W. CHEN ◽

WEI GAO

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Grain Growth ◽

Dihedral Angle ◽

Cast Alloy ◽

Factors Affecting ◽

Constitutional Liquation ◽

Grain Boundary Wetting

In this study, constitutional liquation in AZ91 cast alloy at 440°C and 465°C was experimentally simulated. Metallurgical examination was conducted to reveal the morphology of the constitutional liquid and dihedral angle was measured to evaluate the wettability of the liquid on grain boundary. Dihedral angle was found to be initially ~30 degree and thus grain boundaries were incomplete wet. During annealing, the metastable constitutional liquid resolidified, followed by grain growth. The extent of grain boundary wetting by the remaining liquid increased slightly with treating time. The rate of resolidification was also evaluated and the factors affecting this rate were discussed.

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Embrittlement of Steels by Liquid Zinc: Crack Propagation after Grain Boundary Wetting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.922.161 ◽

2014 ◽

Vol 922 ◽

pp. 161-166 ◽

Cited By ~ 4

Author(s):

Renaud Frappier ◽

Pascal Paillard ◽

René Le Gall ◽

Thomas Dupuy

Keyword(s):

Grain Boundary ◽

Crack Propagation ◽

Grain Boundaries ◽

Tensile Elongation ◽

Crack Propagation Rate ◽

High Strength ◽

Propagation Rate ◽

Atomic Scale ◽

Temperature Range ◽

Grain Boundary Wetting

This study characterizes the mechanical behavior of an advanced multiphase high strength steel by means of high temperature tensile testing. The results show a drastic reduction of the maximum tensile elongation from around 700 °C up to 950°C. Scanning electron microscopy investigations show that the temperature range for embrittlement is correlated with the total wetting of steel grain boundaries. Under external strain, crack propagates along the grain boundaries according to a mechanism that leads to the presence of nanometer-thick films of Zn at the crack tip, as shown by fine X-ray spectroscopy analyses. The effective temperature range for embrittlement is discussed. Mechanisms of i) external stress-free wetting, and ii) atomic-scale crack propagation, are today under discussion in the light of the literature, regarding in particular recent experimental results and theory about grain boundary wetting, intergranular penetration, and the correlation between surface energy and crack propagation rate.

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Measurement of the Displacement Across a Coincidence Grain Boundary

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078213 ◽

1977 ◽

Vol 35 ◽

pp. 124-125

Author(s):

J. W. Matthews ◽

W. M. Stobbs

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Stacking Fault ◽

The Other ◽

Measuring Technique ◽

High Angle ◽

Twin Boundaries ◽

Rigid Displacement ◽

Cubic Crystals ◽

Lattice Displacement

Many high-angle grain boundaries in cubic crystals are thought to be either coincidence boundaries (1) or coincidence boundaries to which grain boundary dislocations have been added (1,2). Calculations of the arrangement of atoms inside coincidence boundaries suggest that the coincidence lattice will usually not be continuous across a coincidence boundary (3). There will usually be a rigid displacement of the lattice on one side of the boundary relative to that on the other. This displacement gives rise to a stacking fault in the coincidence lattice.Recently, Pond (4) and Smith (5) have measured the lattice displacement at coincidence boundaries in aluminum. We have developed (6) an alternative to the measuring technique used by them, and have used it to find two of the three components of the displacement at {112} lateral twin boundaries in gold. This paper describes our method and presents a brief account of the results we have obtained.

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Observations of dislocation interactions with recrystallized grain boundaries

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105205 ◽

1988 ◽

Vol 46 ◽

pp. 628-629

Author(s):

C. W. Price

Keyword(s):

Dislocation Density ◽

Grain Boundary ◽

Strain Rate ◽

Grain Boundaries ◽

Dislocation Structure ◽

Hot Deformation ◽

Static Recrystallization ◽

High Dislocation Density ◽

High Angle ◽

Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

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Measurement of solute segregation to grain boundaries in the AEM: A review

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105096 ◽

1988 ◽

Vol 46 ◽

pp. 606-607

Author(s):

D. B. Williams ◽

A. D. Romig

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Boundary Migration ◽

Grain Boundary Migration ◽

Boundary Misorientation ◽

Collector Plate ◽

Segregation Process ◽

Grain Boundary Misorientation ◽

Structure Boundary ◽

Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

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