Localized dissolution of grain boundary T1 precipitates in Al-3Cu-2Li

2015 ◽  
Vol 33 (6) ◽  
pp. 395-401 ◽  
Author(s):  
Ramasis Goswami
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Orientation Relationship ◽  
S Phase ◽  
Dissolution Behavior ◽  
Moist Air ◽  
Orientation Relation ◽  
Transmission Electron ◽  
Relationship Of

AbstractTransmission electron microscopy (TEM) was employed to investigate the dissolution behavior of nanocrystalline grain boundary T1 precipitates in Al-3Cu-2Li. These grain boundary T1 plates exhibit an orientation relation with matrix, with the (1-11)α-Al parallel to (0001)T1 and [022]α-Al parallel to [10-10]T1, which is similar to the orientation relationship of T1 plates formed within grains. TEM studies showed that these grain boundary T1 plates react readily in moist air. As a result of the localized dissolution, the Cu-rich clusters form onto T1, which is consistent with the localized dissolution behavior observed in nanocrystalline S phase in Al-Cu-Mg.

Epitaxial Gold in Au/Si Eutectic Reaction and Epitaxial Aluminum Spikes in Al-1%Si/Ti-W/Si System

1988 ◽  
Vol 116 ◽  
Author(s):  
Peng-Heng Chang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Epitaxial Growth ◽  
Orientation Relationship ◽  
Gold Film ◽  
Eutectic Reaction ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Relationship Of ◽  
The Relationship

AbstractEpitaxial regrowth of gold film on Si as a result of Au/Si eutectic reaction and epitaxial aluminum spikes forming at IC contacts during sintering have been investigated by transmission electron microscopy (TEM). For gold film on Si, three types of epitaxy were observed: (1) the crystal structures of the two lattices are exactly the same, (2) the two structures have the orientation relationship of Au(111)//Si(111) and Au[132]//Si[231] and (3) 20° misorientation from the relationship in (2). Two orientation relationships were observed in the case of Al spike in Si: (1) Al[011]//Si[123] and Al(200)//Si(11), (2) Al[001]//Si[112] and 2° misorientation between Al(200) and Si(111). Possible mechanisms are proposed to explained the observed epitaxial growth.

Transmission Electron Microscopy Observations on Cu-Ti Alloy Systems

2005 ◽  
Vol 502 ◽  
pp. 163-168 ◽  
Author(s):  
Rimi Nishio ◽  
Toyohiko J. Konno ◽  
Satoshi Semboshi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Separation ◽  
Orientation Relationship ◽  
Decomposition Mechanism ◽  
Ti Alloy ◽  
Modulated Structure ◽  
Transmission Electron ◽  
Crystallographic Structures ◽  
Relationship Of

Phase separation behaviors of a quenched Cu-3.0at%Ti alloy, as well as crystallographic structures of Cu-20.7at%Ti alloy have been studied using transmission electron microscopy. The furnacecooled Cu-20.7at%Ti alloy are composed of a-Cu4Ti (Ni4Mo-type) and b-Cu4Ti (Au4Zr-type) with the orientation relationship of (011)a//(110)b, [100]a//[001]b. As-quenched Cu-3.0at%Ti alloy showed a modulated structure with the modulation length of about 4 nm. When aged at 723K for 8 hr, the a-Cu4Ti phase emerges within the modulated or tweed-like microstructure. Prolonged aging results in the growth of the a-Cu4Ti particles and the loss of coherency. It is likely that asquenched Cu-3.0at%Ti alloy decomposes spinodally at 723K, followed by polymorphous ordering; though the present study did not exclude, as an alternative path, a decomposition mechanism based on the catastrophic nucleation.

Metal-ZnO Interfaces Studied by High Resolution Transmission Electron Microscopy

1996 ◽  
Vol 466 ◽  
Author(s):  
J.Th.M. De Hosson ◽  
W. P. Vellinga ◽  
H. B. Groen ◽  
B. J. Kooi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Orientation Relationship ◽  
Internal Oxidation ◽  
Atomic Structure ◽  
Orientation Relation ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
The Matrix

ABSTRACTThis paper reports on investigations of Ag-ZnO and Cu-ZnO interfaces, produced by internal oxidation. ZnO precipitates with the wurtzite structure were found showing mainly one orientation relationship (OR) with the matrix. However, closely related ORs were found, rotated by small angles from that orientation relation. The atomic structure of several interfaces surrounding these precipitates was studied and compared using high resolution transmission electron microscopy. This paper focuses on interfaces between low index facets of ZnO and vicinal planes of Ag. These interfaces clearly show relaxations. An interpretation of these relaxations in terms of dissociation of partial dislocations at the interface is put forward.

High-Resolution Transmission Electron Microscopy Studies of a Near Sigma11 Grain Boundary in alpha-Alumina

1994 ◽  
Vol 77 (2) ◽  
pp. 339-348 ◽  
Author(s):  
Thomas Hoche ◽  
Philip R. Kenway ◽  
Hans-Joachim Kleebe ◽  
Manfred Ruhle ◽  
Patricia A. Morris
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Transmission Electron ◽  
Alpha Alumina

Interfacial precipitation in titania-doped diphasic mullite gels

1998 ◽  
Vol 13 (4) ◽  
pp. 974-978 ◽  
Author(s):  
Seong-Hyeon Hong ◽  
Naesung Lee ◽  
Altaf H. Carim ◽  
Gary L. Messing
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Phase Transformations ◽  
Orientation Relationship ◽  
Sol Gel ◽  
Sintered Body ◽  
Transmission Electron

Interfacial precipitation in sol-gel derived, titania-doped diphasic mullite gels was investigated using conventional and high resolution transmission electron microscopy. Rutile, anatase, and brookite precipitated on the interface between {110} planes of mullite and glass pockets in the sintered body. The formation of brookite may be attributable to the Si- and Al-rich environment during precipitation. Each polymorph of titania has a unique morphology and orientation relationship with mullite. Brookite exhibits a truncated pill box shape, and anatase displays a vermicular morphology. Quenching experiments suggest that the precipitates grow and undergo phase transformations during cooling.

Motion of Crystal/Crystal and Crystal/Amorphous Interfaces

1990 ◽  
Vol 183 ◽  
Author(s):  
J. L. Batstone
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Grain Boundary ◽  
Boundary Motion ◽  
High Temperature Annealing ◽  
Thermally Activated ◽  
Transmission Electron ◽  
Grain Boundary Motion

AbstractMotion of ordered twin/matrix interfaces in films of silicon on sapphire occurs during high temperature annealing. This process is shown to be thermally activated and is analogous to grain boundary motion. Motion of amorphous/crystalline interfaces occurs during recrystallization of CoSi2 and NiSi2 from the amorphous phase. In-situ transmission electron microscopy has revealed details of the growth kinetics and interfacial roughness.

Microstructural Studies of High Coercivity Nd15Fe77B8 Sintered Magnets

1987 ◽  
Vol 96 ◽  
Author(s):  
M. H. Ghandehari ◽  
J. Fidler
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Electron Microprobe ◽  
Boundary Phase ◽  
High Coercivity ◽  
Transmission Electron ◽  
Microstructural Studies ◽  
Domain Reversal

ABSTRACTMicrostructures of Nd15−xDyxFe77B8 prepared by alloying with Dy, and by using Dy2O3 as a sinl'ken adidive, have been determined using electron microprobe and transmission electron microscopy. The results have shown a higher Dy concentration near the grain boundaries of the 2–14–1 phase for magnets doped with Dy2O 3, as compared to the Dy-alloyed magnets. A two-step post sintering heat treatment was also studied for the two systems. The resultant concentration gradient of Dy in the 2–14–1 phase of the oxide-doped magnets is explained by the reaction of Dy2O3 with the Nd-rich grain boundary phase and its slow diffusion into thg 4–14–1 phase. Increased Dy concentration near the grain boundary is more effective in improving the coercivity, as domain reversal nucleation originates at or near this region.

Structural transformation of a kaolinite and calcite mixture to gehlenite and anorthite

2003 ◽  
Vol 18 (2) ◽  
pp. 475-481 ◽  
Author(s):  
Karfa Traoré ◽  
Philippe Blanchart
Keyword(s):  
Electron Microscopy ◽  
Phase Diagram ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Low Temperature ◽  
Orientation Relationship ◽  
Interlayer Spacing ◽  
Direct Transition ◽  
Transmission Electron ◽  
Successive Phase

Kaolinite mixed with calcite was sintered at low temperature (1100 °C; 5 °C/min). The successive phase transformations are metakaolinite to gehlenite and then anorthite, although the available phase diagram indicates a direct anorthite recrystallization. Transmission electron microscopy and electron diffraction studies of nanocrystallites revealed that the transformation path is favored by the structural similarities of phases. In particular, the pseudolayers of gehlenite have a major orientation relationship with the initial metakaolinite layers. The gehlenite axis, [001]G, is parallel to the metakaolinite axis, [001]A. This direct transition is favored by the existence of Si tetrahedral units and 4–fold–coordinated Al in both structures. Ca atoms, initially in the interlayer spacing of metakaolinite, remain in the interlayers of gehlenite. During the second transformation step, anorthite recrystallizes from gehlenite with axis [020]A parallel to [210]G. It is proposed that this orientation relationship is favored by the orientation and shape of Ca-atom channels through both structures, along [001]G and [100]A axes.

In situ x-ray study of the γ- to α-Al2O3 phase transformation during atmospheric pressure oxidation of NiAl(110)

2006 ◽  
Vol 21 (12) ◽  
pp. 3047-3057 ◽  
Author(s):  
A. Vlad ◽  
A. Stierle ◽  
N. Kasper ◽  
H. Dosch ◽  
M. Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Orientation Relationship ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Oxidation In Air ◽  
Α Al2o3 ◽  
Underlying Substrate

The oxidation in air of NiAl(110) was investigated in the temperature range from 870 °C–1200 °C by in situ x-ray diffraction and transmission electron microscopy. Oxidation at 870 °C and 1 bar oxygen leads to the formation of an epitaxial layer of γ-alumina showing an R30° orientation relationship with respect to the underlying substrate. At oxidation temperatures between 950 °C and 1025 °C, we observed a coexistence of epitaxial γ- and polycrystalline δ-Al2O3. The α-Al2O3 starts to form at 1025 °C and the complete transformation of metastable phases to the stable α-alumina phase takes place at 1100 °C. The fcc-hcp martensitic-like transformation of the initial γ-Al2O3 to epitaxial α-Al2O3 was observed. X-ray diffraction and cross-section transmission electron microscopy proved the existence of a continuous epitaxial α-Al2O3 layer between the substrate and the polycrystalline oxide scale, having a thickness of about 150 nm. The relative orientation relationship between the epitaxial alumina and the underlying substrate was found to be NiAl(110) || α-Al2O3 (0001) and [110] NiAl || [1120].

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