Effects of Antiphase Domain Size and Twin Platelet Width on the Hardness of an Ordered CuAu Alloy

1994 ◽  
Vol 362 ◽  
Author(s):  
Takanobu Shiraishi ◽  
Michio Ohta ◽  
Masaharu Nakagawa
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
Continuous Growth ◽  
X Ray ◽  
Structure Changes ◽  
Transmission Electron ◽  
Three Stages ◽  
Twin Spacing ◽  
Coherency Strains ◽  
Disordered Alloy

AbstractEffects of antiphase domain (APD) size and inter-twin spacing on the hardness of CuAu I-phase in the overaging stage were investigated by hardness testing, transmission electron microscopy, and X-ray powder diffraction. Overaging in CuAu I-phase upon progressive ordering at 300°C was found to proceed through three stages: stages I through III. In the stage I, twinning actively occurred, and most of the coherency strains were removed. Average inter-twin spacing slightly increased. These microstructural evolutions slightly decreased the hardness of the alloy. In the stage II, both APD size and average inter-twin spacing grew larger with time, leading to a continuous decrease in hardness. In the stage III, the APD size markedly grew larger, while the growth rate of average inter-twin spacing markedly slowed down. The continuous growth of APD size apparently contributed to the further decrease in hardness. Although the crystal structure changes during the CuAu I ordering, a perfectly ordered alloy with no planar defects was suggested to be not so strong as the corresponding disordered alloy.

Antiphase Boundaries in Ordered Ni3FE Crystals

1969 ◽  
Vol 27 ◽  
pp. 62-63
Author(s):  
Y. H. Liu
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardening Mechanism ◽  
Superlattice Structure ◽  
Disordered Phase ◽  
Domain Boundaries ◽  
Atomic Scattering ◽  
The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

scholarly journals Structural Changes of Mo/ZSM-5 Catalysts During the Methane Dehydroaromatization

2009 ◽  
Vol 12 (1) ◽  
pp. 9 ◽  
Author(s):  
Z.R. Ismagilov ◽  
E.V. Matus ◽  
I.Z. Ismagilov ◽  
M.A. Kerzhentsev ◽  
V.I. Zailovskii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Atomic Ratio ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Structure Changes ◽  
Transmission Electron ◽  
Methane Dehydroaromatization ◽  
Naoh Treatment ◽  
Mo Content

<p>The structure changes of Mo/ZSM-5 catalysts with different Mo content (2 and 10 wt. % Mo) and Si/Al atomic ratio (17, 30 and 45) during the methane dehydroaromatization have been investigated by X-ray powder diffractometry, N<sub>2</sub> adsorption and transmission electron microscopy. The treatment of Mo/ZSM-5 catalysts in reducing atmosphere (CH<sub>4</sub> or H<sub>2</sub>) at about 700 °C promotes development of mesoporous system. The pores are open to the exterior of the zeolite grain and have an entrance diameter of ~ 4-10 nm. It is proposed that mesopore formation in Mo/ZSM-5 catalyst is connected with the dealumination of zeolite. The mesopore formation in the parent H-ZSM-5 zeolite by NaOH treatment does not improve the activity of /ZSM-5 catalyst.</p>

Structure and Strength of Rapidly Quenched Cu-Al2O3 Composites

1998 ◽  
Vol 555 ◽  
Author(s):  
A. I. Il'Insky ◽  
A. S. Terletsky ◽  
E. W. Zozulya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Strain Hardening ◽  
Vapor Condensation ◽  
High Temperature Annealing ◽  
X Ray ◽  
Transmission Electron ◽  
Three Stages ◽  
High Level

AbstractMicrostructure of dispersion hardened composites (DC) Cu-Al2O3 prepared by simultaneous vacuum vapor condensation of Cu and A12O3 was studied by X-ray diffractometry and transmission electron microscopy methods. After high temperature annealing at 900°C for 2 hours the composites retain the submicrocrystalline structure and high level of strength -0.9 GPa. It has been found that strain hardening of vacuum deposited Cu-A12O3 composites takes place in three stages that is not typical for well-known composites of metallurgical origin.

The Disorder-Order Transformation in Ni4Mo

1971 ◽  
Vol 15 ◽  
pp. 319-329 ◽  
Author(s):  
Fu-Wen Ling ◽  
E. A. Starke
Keyword(s):  
Order Parameter ◽  
Domain Size ◽  
Antiphase Domain ◽  
Domain Growth ◽  
Range Order Parameter ◽  
Line Broadening ◽  
Kcal Mole ◽  
X Ray ◽  
Isothermal Ageing ◽  
Internal Strains

The progressive ordering of a single crystal of Ni4Mo by isothermal ageing at 650°C (transformation temperature = 868°C) has been studied by x-ray line broadening techniques using the Warren- Averbach method employing computer techniques. The long-range-order parameter, antiphase domain size, and internal strains were measured as a function of ordering time and compared with those previously obtained at 700°C. The activation energies for domain growth and ordering were found to be 91 kcal/mole and 44.5 kcal/mole respectively. The rms strain developed during ordering was found to be dependent on the degree of tetragonality of the structure.

scholarly journals Complementary use of monochromatic and white-beam X-ray micro-diffraction for the investigation of ancient materials

2015 ◽  
Vol 48 (5) ◽  
pp. 1522-1533 ◽  
Author(s):  
Catherine Dejoie ◽  
Nobumichi Tamura ◽  
Martin Kunz ◽  
Philippe Goudeau ◽  
Philippe Sciau
Keyword(s):  
Single Crystal ◽  
Hybrid Approach ◽  
Domain Size ◽  
Heating Process ◽  
X Ray ◽  
Structure Information ◽  
Specific Distribution ◽  
Transmission Electron ◽  
Ancient Times

Archaeological artefacts are often heterogeneous materials where several phases coexist in a wide grain size distribution. Most of the time, retrieving structure information at the micrometre scale is of great importance for these materials. Particularly, the organization of different phases at the micrometre scale is closely related to optical or mechanical properties, manufacturing processes, functionalities in ancient times and long-term conservation. Between classic X-ray powder diffraction with a millimetre beam and transmission electron microscopy, a gap exists and structure and phase information at the micrometre scale are missing. Using a micrometre-size synchrotron X-ray beam, a hybrid approach combining both monochromatic powder micro-diffraction and Laue single-crystal micro-diffraction was deployed to obtain information from nanometre- and micrometre-size phases, respectively. Therefore providing a way to bridge the aforementioned gap, this unique methodology was applied to three different types of ancient materials that all show a strong heterogeneity. In Romanterra sigillata, the specific distribution of nanocrystalline hematite is mainly responsible for the deep-red tone of the slip, while the distribution of micrometre-size quartz in ceramic bodies reflects the change of manufacturing process between pre-sigillataand high-qualitysigillataperiods. In the second example, we investigated the modifications occurring in Neolithic and geological flints after a heating process. By separating the diffracted signal coming from the nano- and the micrometre scale, we observed a domain size increase for nanocrystalline quartz in geological flints and a relaxation of the residual strain in larger detritic quartz. Finally, through the study of a Roman iron nail, we showed that the carburation process to strengthen the steel was mainly a surface process that formed 10–20 µm size domains of single-crystal ferrite and nanocrystalline cementite.

Partial cation-order and early-stage, phase separation in phase W, Li x Co 1− x O: 0.075≤ x ≤0.24−0.31

2009 ◽  
Vol 465 (2106) ◽  
pp. 1829-1841 ◽  
Author(s):  
Y. Wu ◽  
D. Pasero ◽  
E.E. McCabe ◽  
Y. Matsushima ◽  
A.R. West
Keyword(s):  
Phase Separation ◽  
Early Stage ◽  
Domain Size ◽  
Solid Solution Phase ◽  
X Ray ◽  
Cation Order ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Li Content ◽  
Disordered Regions

We report the characterization using X-ray and neutron powder diffraction, transmission electron microscopy and extended X-ray absorption fine structure of a new, partially ordered rock-salt-like solid solution phase Li x Co 1− x O: 0.075≤ x ≤0.24−0.31. The cation stacking sequence along [111] consists of alternating planes of Co and Co/Li. Nano-sized domains of this cation-ordered phase appear alongside disordered regions; domain size increases from 2 to 8 nm with increasing Li content. Compositions of ordered and disordered regions are Li- and Co-rich, respectively, and, therefore, the phase exhibits frozen-in, incipient phase separation. This microstructure could be considered as a precursor to precipitation of fully ordered, rhombohedral LiCoO 2 .

On the Structural Evolution of the Amorphous Al75Cu15V10 Alloy to the Icosahedral Phase

1988 ◽  
Vol 43 (5) ◽  
pp. 505-506 ◽  
Author(s):  
E. Matsubara ◽  
Y. Waseda ◽  
A. P. Tsai ◽  
A. Inoue ◽  
T. Masumoto
Keyword(s):  
Electron Microscopy ◽  
Structural Evolution ◽  
Icosahedral Phase ◽  
X Ray Diffraction ◽  
Bright Field ◽  
Continuous Growth ◽  
X Ray ◽  
Transmission Electron ◽  
Icosahedral Clusters ◽  
Peak Widths

The transformations occurring on annealing an as-spun amorphous Al75Cu15V10 alloy are studied by X-ray diffraction and transmission electron microscopy (TEM). A continuous growth of icosahedral clusters, which are present already in the as-spun sample, is revealed. The size of the clusters estimated from the diffuse X-ray peak widths is consistent with the size of the modulation observed in the bright field TEM images.

Microstructural changes in porous hematite nanoparticles upon calcination

2011 ◽  
Vol 44 (3) ◽  
pp. 495-502 ◽  
Author(s):  
Rune E. Johnsen ◽  
Kenneth D. Knudsen ◽  
Alfons M. Molenbroek
Keyword(s):  
Adsorption Isotherm ◽  
Surface Area ◽  
Small Angle Neutron Scattering ◽  
Particle Sizes ◽  
X Ray ◽  
Structure Changes ◽  
Transmission Electron ◽  
Porous Microstructure ◽  
Void Structure ◽  
Sans Data

This combined study using small-angle neutron scattering (SANS), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and adsorption isotherm techniques demonstrates radical changes in the microstructure of porous hematite (α-Fe2O3) nanoparticles upon calcination in air. TEM images of the as-synthesized hematite sample show that it consists of subrounded nanoparticles [50 (8)–61 (11) nm in average minimum and maximum diameters] with an apparent porous structure of nanosized pores/channels or cracks. SANS data confirm the presence of two characteristic sizes, one originating from the particle size and the other from the pore/void structure. Furthermore, the TEM images show that the particle sizes are nearly unaffected by calcination at 623 K, whereas their pore/void structure changes radically to an apparently pitted or spongy microstructure with cavities or/and voids. The change in microstructure also causes a reduction in the surface area as calculated by gaseous adsorption. The XRPD and SANS data show that the crystallite and SANS particle sizes are virtually unchanged by calcination at 623 K. Calcination at 973 K induces a significant alteration of the sample. The XRPD data reveal that the crystallite size increases significantly, and the SANS and adsorption isotherm studies suggest that the specific surface area decreases by a factor of ∼5–6. The TEM images show that the particles are sintered into larger agglomerates, but they also show that parts of the porous microstructure observed in the sample calcined at 623 K are retained in the sample calcined at 973 K.

scholarly journals Direct Transformation of Crystalline MoO3 into Few-Layers MoS2

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2293
Author(s):  
Felix Carrascoso ◽  
Gabriel Sánchez-Santolino ◽  
Chun-wei Hsu ◽  
Norbert M. Nemes ◽  
Almudena Torres-Pardo ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Domain Size ◽  
X Ray Diffraction ◽  
Large Area ◽  
Direct Transformation ◽  
X Ray ◽  
Transmission Electron ◽  
Complementary Techniques ◽  
P Type ◽  
20 Nm

We fabricated large-area atomically thin MoS2 layers through the direct transformation of crystalline molybdenum trioxide (MoO3) by sulfurization at relatively low temperatures. The obtained MoS2 sheets are polycrystalline (~10–20 nm single-crystal domain size) with areas of up to 300 × 300 µm2, 2–4 layers in thickness and show a marked p-type behavior. The synthesized films are characterized by a combination of complementary techniques: Raman spectroscopy, X-ray diffraction, transmission electron microscopy and electronic transport measurements.

scholarly journals DOMAIN SIZE DISTRIBUTION OF Y-TZP NANO-PARTICLES USING XRD AND HRTEM

2011 ◽  
Vol 20 (3) ◽  
pp. 157 ◽  
Author(s):  
Florence Boulc'h ◽  
Marie-Claude Schouler ◽  
Patricia Donnadieu ◽  
Jean-Marc Chaix ◽  
Elisabeth Djurado
Keyword(s):  
Size Distribution ◽  
Spray Pyrolysis Technique ◽  
Domain Size ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Tetragonal Form ◽  
Scherrer Formula ◽  
Average Size

Yttria doped nanocrystalline zirconia powder was prepared by spray-pyrolysis technique. Powder crystallized into tetragonal form, as dense and compositionally homogeneous polycrystalline spheres. X-Ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) have been used in order to characterize the mean size and the size distribution of crystalline domains. An average size of 6 nm was calculated by Scherrer formula from X-Ray diffraction pattern. The domain size, determined by analysis method developed by Hytch from HRTEM observations, ranges from 5 to 22 nm with a main population around the value 12 nm. Limits and complementary nature of XRD and HRTEM methods are discussed.

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