HRTEM Observation of Precipitates in Mg-Gd-Zr and Mg-Y-Zr Alloys Aged at 423 K

2012 ◽  
Vol 706-709 ◽  
pp. 1205-1208
Author(s):  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Early Stage ◽  
Magnesium Matrix ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Peak Aged ◽  
Zr Alloy ◽  
Zr Alloys

High resolution transmission electron microscopy (HRTEM) observation was performed to clarify the early stage of precipitation in Mg-Gd (-Zr) alloy and Mg-Y(-Zr) alloy aged at 423 K. At the early stage of agigng at 423 K, the intensity of the diffuse spots become higher at the 1/2 distance of 1100 or 2110 corresponding to magnesium matrix spots with aging time. Contrasts of mono layers on {100}Mgplanes, and the feature of D019type structure, precipitates with five layers corresponding the feature of (020)b'plane and b' phase co-existed and b' phase formed predominantly in the peak aged Mg-Gd (-Zr) alloy at 423 K, wheres in the peak aged Mg-Y(-Zr) alloy at 423 K, monolayer and precursor of precipitates with five layers corresponding the feature of (020)b'plane formed predominantly.

HRTEM Observation of the Precipitates in Heat-Resistant Mg-Gd-Y-Zr Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 1769-1774 ◽  
Author(s):  
Tokimasa Kawabata ◽  
Yuya Fukuda ◽  
Kenji Matsuda ◽  
Shigeharu Kamado ◽  
Yo Kojima ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Lattice Structure ◽  
Early Stage ◽  
Aged Specimen ◽  
Β Phase ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Peak Aged ◽  
Zr Alloy

The high resolution transmission electron microscope (HRTEM) observation was carried out to investigate the microstructure of precipitates in Mg-Gd-Y-Zr alloy. In the early stage of aging at 423K, monoatomic layers were observed along the (1 1 00)Mg plane. After 64h aging at 423K, the contrast of β” phase based on ordered D019 hexagonal super lattice structure was appeared. The monoatomic layers, two layers spaced by (1 1 00) Mg planes and β’ phase based on bco-structure were observed in the specimen aged for 128h. In the peak- aged specimen, the β’ phase and monoatomic layers were observed.

HRTEM Observation of the Age Hardening Precipitates in Mg-Zn Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 157-160
Author(s):  
Shogo Mori ◽  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Early Stage ◽  
Age Hardening ◽  
Aged Specimen ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Peak Aged ◽  
Zn Alloy ◽  
Different Parts

The age hardening precipitates of Mg-4.7mass%Zn alloy aged at 423K,473K were studied by using high-resolution transmission electron microscope (HRTEM). Contrasts of mono layers were confirmed to exist on the (0001) and (1100) matrix planes. It was considered that the contrast of mono layer was plate-like shape, and identified as pre-precipitates from as-quenched stage to early stage of aging at 473K for 32h . In the peak aged specimen of aged at 473K, the β1’ phase was observed. The β1’ phase has a rod-like shape and parallel to c-axis of Mg matrix. It can be observed orientation relationship between Mg matrix and β1’phase has not only same parts to previous reports but also different parts in one β1’ phase .

High-resolution transmission electron microscopy (HRTEM) observation of dislocation structures in AlN thin films

2008 ◽  
Vol 23 (8) ◽  
pp. 2188-2194 ◽  
Author(s):  
Yuki Tokumoto ◽  
Naoya Shibata ◽  
Teruyasu Mizoguchi ◽  
Masakazu Sugiyama ◽  
Yukihiro Shimogaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Film Growth ◽  
Threading Dislocations ◽  
Organic Vapor ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Metal Organic ◽  
Edge Dislocations

The structure and configuration of threading dislocations (TDs) in AlN films grown on (0001) sapphire by metal–organic vapor phase epitaxy (MOVPE) were characterized by high-resolution transmission electron microscopy (HRTEM). It was found that the TDs formed in the films were mainly the perfect edge dislocations with the Burgers vector of b = ⅓〈11¯20〉. The majority of the edge TDs were not randomly formed but densely arranged in lines. The arrays of the edge TDs were mainly observed on the {11¯20} and {10¯10} planes. These two planes showed different configurations of TDs. TD arrays on both of these planes constituted low-angle boundaries. We suggest that these TDs are introduced to compensate for slight misorientations between the subgrains during the film growth.

Microstructure - Roughness Interelation in Ru/C and Ru/B4C X-RAY Multilayers

1992 ◽  
Vol 280 ◽  
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortricht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Diffuse Component ◽  
Interfacial Roughness ◽  
Cross Sectional ◽  
X Ray ◽  
Specular Scattering ◽  
Transmission Electron ◽  
Hrtem Observation

ABSTRACTX-ray specular and non-specular scattering, and high-resolution transmission electron microscopy (HRTEM) were performed to study the evolution of the microstructures and interfacial roughness in Ru/C and RU/B4C multilayers upon annealing. The microstructure of the approximately 1.4 nm thick Ru layers in the as-prepared 3.5 nm period multilayers is predominantly amorphous. The Ru layers in the Ru/B4C multilayer show RuB2nano-crystallites after annealing at 600°C for one hour, while those in the Ru/C multilayer crystallize to form hexagonal Ru crystallites. Cross-sectional HRTEM of the annealed Ru/C multilayer also shows agglomeration of the Ru layers. Non-specular measurements of the Ru/C multilayers indicate an enhanced uncorrelated roughness upon annealing. The diffuse component in the as-prepared and annealed RU/B4C multilayers shows insignificant changes. The increase in interfacial roughness in the Ru/C multilayer results from agglomeration of the Ru after annealing, consistent with HRTEM observation.

Study of Precipitation Sequence in Al-Mg-Si Alloys by HRTEM

2005 ◽  
Vol 475-479 ◽  
pp. 361-364 ◽  
Author(s):  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Low Temperature ◽  
Early Stage ◽  
Metastable Phases ◽  
Precipitation Sequence ◽  
Mono Layer ◽  
Transmission Electron

The precipitation sequence of Al-Mg-Si alloys has been studied by high-resolution transmission electron microscopy (HRTEM). G.P. zone is a fine-plate having dimensions of a mono- layer in thickness, 2.5nm in width, and less than 30nm in length. Its elongated direction is parallel to the <100>m direction. Several types of metastable phases were observed in the excess Si alloy and they were classified with the b ’-phase in the balanced alloy. Especially, the b ”-phase was the typical phase in the excess Si alloy aged at low temperature or at the early stage during aging.

HRTEM Observation of Precipitates at Early Stage of Aging in Mg-Gd-Zr Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 303-306 ◽  
Author(s):  
Tokimasa Kawabata ◽  
Toshiyuki Matsuno ◽  
Kenji Matsuda ◽  
Shigeharu Kamado ◽  
Yo Kojima ◽  
...  
Keyword(s):  
Early Stage ◽  
Peak Hardness ◽  
Aged Specimen ◽  
Β Phase ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Peak Aging ◽  
Peak Aged ◽  
Aging Stage ◽  
Zr Alloy

High resolution transmission electron microscopy（HRTEM）observation was performed to clarify morphology of precipitates at early stage of aging in Mg-Gd-Zr alloy. In the specimen aged at 423K, monolayer was observed on {1100}Mg planes. With increasing aging time, the monolayer and β” phase grew along the <1120>Mg directions. Arrangement of bright dots corresponding to {020}β’ except for the monolayer and β” phase was observed before peak aging stage. β’ phases formed at the same aging stage. Thus, these precipitates co-existed before peak aging stage. The monolayer, β” phase and β’ phase still co-existed in the peak aged specimen. The β’ phase was dominated in the peak hardness. It is revealed that the monolayer lying on {1100}Mg act as precursor of β” phase and β’ phase.

Age-Hardening Behaviour and HRTEM Observation of Precipitates in Excess Mg Type Al-Mg-Si-Ag Alloy

2006 ◽  
Vol 519-521 ◽  
pp. 507-510 ◽  
Author(s):  
Azusa Furihata ◽  
Kenji Matsuda ◽  
Junya Nakamura ◽  
Susumu Ikeno ◽  
Yasuhiro Uetani
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Age Hardening ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Excess Mg

In this work, the age-hardening of Al- 1.0 mass% Mg2Si- 0.4 mass% Mg – 0.5 mass% Ag (ex.Mg-Ag alloy) alloy has been investigated. It showed increase of hardness and age-hardening response. Precipitates in this alloy aged at 523 K have been observed by high resolution transmission electron microscopy (HRTEM) and classified into five types based on characteristics in their HRTEM images.

scholarly journals Tem Observation Of Age-Hardening Precipitation In Mg-Gd-Y Alloys As Different Gd/Y Ratio

2015 ◽  
Vol 60 (2) ◽  
pp. 971-972
Author(s):  
Y. Matsuoka ◽  
K. Watanabe ◽  
J. Nakamura ◽  
W. Lefebvre ◽  
S. Saikawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Early Stage ◽  
Dark Field ◽  
Age Hardening ◽  
Transmission Electron ◽  
Overlap Population ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Peak Aged

Abstract In this study, the early stage of aging in Mg-Gd-Y alloys has been observed by transmission electron microscopy (TEM), high angle annular dark field – scanning transmission electron microscopy (HAADF-STEM) and calculations of images and electron density and bond overlap population (BOP) by first principal to understand the origin of precipitation in this alloy. The small hexagon of 0.37 nm is the first precipitate in this alloy, and this is the evidence of short range ordering of D019 structure. This is referred as the pre β”-phase. In the peak aged condition, β’ phase with bco structure was mainly observed.

TEM Observation of Precipitates in a Mg-Gd-Sc Alloy with High Content of Sc

2010 ◽  
Vol 654-656 ◽  
pp. 627-630 ◽  
Author(s):  
Takafumi Fujii ◽  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aging Time ◽  
Number Density ◽  
Maximum Hardness ◽  
Magnesium Matrix ◽  
Β Phase ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Zr Alloy

Precipitates in a Mg–Gd–Sc alloy with high Sc content (up to 13mass%) were examined by means of transmission electron microscopy. Plate-like precipitates appeared during the early stages of aging of specimens aged at 573 K. The plate-like precipitates lay on the { } magnesium matrix planes, and were similar to the β1 phase and β phase in the counterpart Mg–Gd–Zr alloy aged at 523 K. These precipitates had a high Sc content. Particle-shaped precipitate were observed alongside the plate-like precipitates, unlike the case in Mg–Gd alloys. The contrasts of the plate-like precipitates became longer and the number density of precipitate contrasts increased with increasing aging time at 573 K up to the point where the maximum hardness was attained. We suggest that the plate-like precipitates contribute to the increased hardness of Mg–Gd–Sc alloys with a high content of Sc.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Sign in / Sign up

Export Citation Format

Share Document