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 .

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.

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 Rod-Shape Precipitates in Al-Mg-Si-Ag Alloy Aged at 523 K

2007 ◽  
Vol 561-565 ◽  
pp. 243-246 ◽  
Author(s):  
Junya Nakamura ◽  
Kenji Matsuda ◽  
Yoshio Nakamura ◽  
Tatsuo Sato ◽  
Susumu Ikeno
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
High Resolution ◽  
Electron Diffraction ◽  
Metastable Phase ◽  
X Ray ◽  
Β Phase ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Hrtem Observation

The purpose of this study is to identify the crystal structure of metastable phase in Ag added Al-Mg-Si alloy to compare the formation of β’-phases in Al-Mg-Si alloys without Ag, using images of high resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED) patterns and an energy dispersive X-ray spectroscopy (EDS). The result of SAED patterns and HRTEM images have been simulated and compared with images then SAED patterns obtained from actual precipitates. SAED patterns and HRTEM images obtained from metastable phase in the Ag added Al-Mg-Si alloy showed similar to those of β’-phase in Al-Mg-Si alloy without Ag and the lattice spacings changed because of the effect of Ag.

HRTEM Observation of Early Stage of Precipitation in Mg-Gd-Y Alloys

2011 ◽  
Vol 409 ◽  
pp. 350-353
Author(s):  
Daisuke Nakagawa ◽  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Aging Time ◽  
Early Stage ◽  
Saed Pattern ◽  
Peak Hardness ◽  
Aged Specimen ◽  
Β Phase ◽  
Hrtem Observation ◽  
Peak Aged ◽  
Aging Stage

HRTEM observation was performed to clarify the early stage of precipitation in Mg-Gd-Y alloy aged at 473 K. The hardness increased with increasing aging time after quenching. The hardness increased slowly at early stage of aging, increased rapidly, and then reached to peak hardness. At as-quenching and the early stage of aging, the weak spots appeared at a half 100Mgin SAED pattern. The intensity of these weak spots changed to higher with increasing aging time. Monolayers on {100}Mgplanes and β” phase existed at this aging stage. Monolayers, β” phase, the precipitates with five layers corresponding the feature of (020)β’plane and β’ phase co-existed after the rapidly increasing of hardness. In the peak aged specimen at 473 K, both of β” and β’ phases co-existed and β’ phase were formed dominantly.

HRTEM Observation of the Age Hardening Precipitates in Mg-Gd-Sc Alloys, with Different Gd Concentrations

2011 ◽  
Vol 409 ◽  
pp. 335-338
Author(s):  
Takafumi Fujii ◽  
Kenji Matsuda ◽  
Tokimasa Kawabata ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Age Hardening ◽  
Number Density ◽  
Maximum Hardness ◽  
Β Phase ◽  
Transmission Electron ◽  
Hrtem Observation

High resolution transmission electron microscope (HRTEM) observations were performed to investigate the age hardening precipitates in Mg-Gd-Sc alloys. The maximum hardness of these alloys increased with Gd content. The precipitates with the features of β” phase and β’ phase in Mg-Gd alloy were observed in Mg-15Gd-6.4Sc and Mg-10Gd-6.4Sc alloys. Maximum hardness and number density of precipitate in Mg-15Gd-6.4Sc alloy were higher than that in Mg-10Gd-6.4Sc alloy, and the finer precipitates with higher number of density were contributed to the maximum hardness in Mg-Gd-Sc alloys.

Crystal structure and defects of Zr4Co4Si7 (V-phase) investigated by high resolution transmission electron microscope

1997 ◽  
Vol 12 (2) ◽  
pp. 377-384
Author(s):  
J. F. Mao ◽  
H. Q. Ye ◽  
X. G. Ning ◽  
L. L. He ◽  
D. Z. Yang
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Phase Structure ◽  
Structure Type ◽  
Image Simulation ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Coherent Interfaces

The results of high resolution transmission electron microscope (HRTEM) observation and image simulation show that Zr4Co4Si7 possesses the same structure type of Zr4Co4Ge7. Addition of Fe or Ni into the Zr4Co4Si7 compound, except that the dimensions changed slightly, does not change the lattice type and coordination in the crystal structure, maintaining the V-phase structure. Also, twins with coherent boundaries and partially coherent interfaces are observed. The image conditions of Zr4Co4Si7 and the structure differences between Zr4Co4Si7 and tetrahedral close-packed phases are also discussed.

HRTEM Observation of β’-Phase in Cu-40.26 at.% Zn Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 2305-2308
Author(s):  
Masaaki Nishiyama ◽  
Daisuke Hamatani ◽  
Kenji Matsuda ◽  
Tokimasa Kawabata ◽  
Yasuhiro Uetani ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Early Stage ◽  
Phase Decomposition ◽  
Hrtem Image ◽  
Β Phase ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
The Matrix ◽  
Cscl Structure ◽  
Zn Alloy

There have been many reports about the bainitic phase decomposition of annealed Cu-Zn alloy. During annealing at 523 K, the hardness of this alloy increased at the early stage of annealing, although the β-phase couldn't be observed in the matrix of β'-phase (CsCl). The crystal structure of β' phase, thus, was investigated by a high-resolution transmission electron microscopy (HRTEM) to find its structural change. As the result, the striations were observed in the HRTEM image of matrix at the early stage of annealing. The selected area diffraction pattern was also obtained from this area, and it showed the extra streaks which couldn't be explained by the normal CsCl structure of the β’-phase.

The Effect of Ag-Addition on Crystal Structure of β'-Phase in Al-Mg-Si Alloy

2006 ◽  
Vol 519-521 ◽  
pp. 511-514 ◽  
Author(s):  
Junya Nakamura ◽  
Kenji Matsuda ◽  
Yoshio Nakamura ◽  
Tatsuo Sato ◽  
Susumu Ikeno
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
High Resolution ◽  
Metastable Phase ◽  
Ag Addition ◽  
X Ray ◽  
Β Phase ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns

The purpose of this study is identity the crystal structure of metastable phase in Ag added Al-Mg-Si alloy by comparing the β’-phases in Al-Mg-Si alloy without Ag, using images of high resolution transmission electron microscope (HRTEM), selected area electron diffraction patterns (SADPs) and an energy dispersive X-ray spectroscopy (EDS). The result of SADPs and HRTEM images have been simulated and compared with images and SADPs obtained from actual precipitates. SADPs and HRTEM images obtained from metastable phase in the Ag added Al-Mg-Si alloy showed similar to those of β’-phase in Al-Mg-Si alloy without Ag and had different lattice spacings because of the effect of Ag.

HRTEM Observation of the Age Hardening Precipitates in Mg-15wt%Gd-Zr Alloy

2006 ◽  
Vol 15-17 ◽  
pp. 445-448 ◽  
Author(s):  
Toshiyuki Matsuno ◽  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Shigeharu Kamado ◽  
Yo Kojima ◽  
...  
Keyword(s):  
Aging Time ◽  
Precipitation Hardening ◽  
Early Stage ◽  
Atomic Layer ◽  
Age Hardening ◽  
Β Phase ◽  
Hrtem Observation ◽  
Zr Alloy

The TEM observation was performed to investigate the precipitation hardening in Mg-Gd-Zr alloy. Both the β’ and the β” phase coexist in the specimen aged at 473K for 16h. In the specimen aged at 523K, the β’ phase which has base centered orthorhombic (bco) structure was observed at early stage during aging. The β’ phase has a globular shape and four atomic layer periodicity in the [1100]Mg. The β’ phase grew with increasing aging time mainly along the [0001]Mg and the [1100]Mg.

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