Recrystallization and phase transitions in a γ-TiAl-based alloy as observed by ex situ and in situ high-energy X-ray diffraction

2006 ◽  
Vol 54 (14) ◽  
pp. 3721-3735 ◽  
Author(s):  
Klaus-Dieter Liss ◽  
Arno Bartels ◽  
Helmut Clemens ◽  
Slawomir Bystrzanowski ◽  
Andreas Stark ◽  
...  
Keyword(s):  
Phase Transitions ◽  
High Energy ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray

PHASE FORMATION AND TEXTURE DEVELOPMENT IN AG-SHEATHED Bi, Pb(2223) TAPES STUDIED BY DIFFERENT IN-SITU AND EX-SITU DIFFRACTION TECHNIQUES

2000 ◽  
Vol 14 (25n27) ◽  
pp. 2688-2693 ◽  
Author(s):  
E. GIANNINI ◽  
E. BELLINGERI ◽  
F. MARTI ◽  
M. DHALLÉ ◽  
V. HONKIMÄKI ◽  
...  
Keyword(s):  
High Energy ◽  
Texture Development ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scattering Geometry ◽  
Reflection Geometry ◽  
Comparison Of The Results ◽  
In Situ Neutron Diffraction

In-situ and ex-situ high energy (80÷88 keV) X-Ray diffraction from a synchrotron radiation source were performed on multifilamentary Bi, Pb(2223)/Ag tapes using a transmission scattering geometry. Several thermo-mechanical procedures were compared, focusing mainly on the texture development of both Bi, Pb(2212) and Bi, Pb(2223) phases. The effect of the periodic pressing on the texture and on the critical current is elucidated. The texture development of the Bi, Pb(2212) phase prior to its transformation into Bi, Pb(2223) was directly observed in-situ at high temperature by using a dedicated high-energy X-ray compatible furnace and a high resolution Image Plate detector. A sharp increase of the Bi, Pb(2212) grain orientation along the [00l] direction was found to occur only above 750°C. Normal state transport measurements are in full agreement with the formation mechanism and with the texture development observed. A comparison of the results with the ones provided by in-situ neutron diffraction and standard low-energy XRD in a reflection geometry is presented.

Effects of Phosphorus Exposure on Arsenic-Stabilized GaAs 2×4 Surface

1993 ◽  
Vol 312 ◽  
Author(s):  
A. H. Bensaoula ◽  
A. Freundlich ◽  
A. Bensaoula ◽  
V. Rossignol
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Growth Process ◽  
High Energy ◽  
Ex Situ ◽  
Chemical Beam Epitaxy ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
X Ray

AbstractPhosphorus exposed GaAs (100) surfaces during a Chemical Beam Epitaxy growth process are studied using in-situ Reflection High Energy Electron Diffraction and ex-situ High Resolution X-ray Diffraction. It is shown that the phosphorus exposure of a GaAs (100) surface in the 500 – 580 °C temperature range results in the formation of one GaP monolayer.

Phase Transitions and Recrystallization in a Ti-46at%Al-9at%Nb Alloy as Observed by In-Situ High-Energy X-ray Diffraction

2006 ◽  
Vol 980 ◽  
Author(s):  
Klaus-Dieter Liss ◽  
Helmut Clemens ◽  
Arno Bartels ◽  
Andreas Stark ◽  
Thomas Buslaps
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Strain Relaxation ◽  
Reciprocal Lattice ◽  
Lamellar Microstructure ◽  
High Energy ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
X Ray

AbstractHigh-energy synchrotron X-ray diffraction is a powerful tool for bulk studies of materials. In this investigation, it is applied to the investigation of an intermetallic γ-TiAl based alloy with a composition of Ti-46Al-9Nb. The morphology of the reflections on the Debye-Scherrer rings is evaluated in order to approach grain sizes as well as crystallographic correlations. An in-situ heating cycle from room temperature to a temperature above the α-transus temperature has been conducted starting from a massively transformed sample. With increasing temperature the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase transitions, recrystallization processes, and subsequent grain growth can be observed. During cooling to room temperature, crystallographic correlations between the re-appearing γ-phase and the host α-phase, known as the Blackburn correlation, are observed in the reciprocal lattice, which splits into different twinning and domain orientation relationships present in the fully lamellar microstructure.

Humidity-induced phase transitions of ferric sulfate minerals studied by in situ and ex situ X-ray diffraction

2009 ◽  
Vol 94 (11-12) ◽  
pp. 1629-1637 ◽  
Author(s):  
W. Xu ◽  
N. J. Tosca ◽  
S. M. McLennan ◽  
J. B. Parise
Keyword(s):  
Phase Transitions ◽  
Ferric Sulfate ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulfate Minerals

scholarly journals A Study of Recrystallization and Phase Transitions in Intermetallic Titanium Aluminides by In Situ High-Energy X-Ray Diffraction

2007 ◽  
Vol 539-543 ◽  
pp. 1519-1524 ◽  
Author(s):  
Klaus Dieter Liss ◽  
A. Bartels ◽  
Helmut Clemens ◽  
S. Bystrzanowski ◽  
A. Stark ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Titanium Aluminides ◽  
Strain Relaxation ◽  
High Energy ◽  
Internal Stresses ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Heating ◽  
Increasing Temperature

High-energy synchrotron X-ray diffraction is a novel and powerful tool for bulk studies of materials. In this study, it is applied for the investigation of an intermetallic γ-TiAl based alloy. Not only the diffraction angles, but also the morphology of reflections on the Debye-Scherrer rings are evaluated in order to approach lattice parameters and grain sizes as well as crystallographic relationships. An in-situ heating cycle from room temperature to 1362 °C has been conducted starting from massively transformed γ-TiAl which exhibits high internal stresses. With increasing temperature the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase transitions, recrystallization processes, and subsequent grain growth can be observed. The data obtained by high-energy synchrotron X-ray diffraction, extremely rich in information, are interpreted step by step.

Structure-Stability Correlations in Li-ion Battery Cathode Materials

2014 ◽  
Vol 1655 ◽  
Author(s):  
Christopher Patridge ◽  
Corey Love ◽  
Wojtek Dmowski ◽  
David Ramaker ◽  
Michelle Johannes ◽  
...  
Keyword(s):  
Structural Changes ◽  
High Energy ◽  
Ex Situ ◽  
Structure Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Capacity Loss ◽  
Pair Density ◽  
Pdf Analysis

ABSTRACTDetailed structural studies of two lithiated metal oxides, Li2CuO2 and nanoscale LiCoO2, have been carried out using ex situ high-energy X-ray diffraction (XRD) and in situ X-ray absorption spectroscopy (XAS) with the objective of understanding structural changes that might cause capacity loss during cycling. XRD on the cuprate was studied at various states of charge and phase composition, and the bulk state was determined by Rietveld refinement and pair density function (PDF) analysis. Results showed a largely irreversible structural change of the material upon oxidation of Cu2+ as well as CuO formation. The in-situ XAS of the LiCoO2 was analyzed through a difference method to extract the changes in the local structure that occur upon cycling in both the near edge (XANES) and extended region (EXAFS). Results suggest that cycling causes site exchange of the Co and Li ions near the surface of the nanoscale LiCoO2.

Epitaxial GdN/SmN-based superlattices grown by molecular beam epitaxy

MRS Advances ◽  
2017 ◽  
Vol 2 (3) ◽  
pp. 189-194
Author(s):  
Franck Natali ◽  
Joe Trodahl ◽  
Stéphane Vézian ◽  
Antoine Traverson ◽  
Benjamin Damilano ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
High Energy ◽  
Ex Situ ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
Doped Semiconductors ◽  
X Ray ◽  
Resistivity Measurements

ABSTRACTGdN/SmN based superlattices have been grown by molecular beam epitaxy. In-situ reflection high energy electron diffraction was used to evaluate the evolution of the epitaxial growth and the structural properties were assessed by ex-situ X-ray diffraction. Hall Effect and resistivity measurements as a function of the temperature establish that the superlattices are heavily n-type doped semiconductors and the electrical conduction resides in both REN layers, SmN and GdN.

scholarly journals In-Situ High-Energy X-ray Diffraction Study of Austenite Decomposition During Rapid Cooling and Isothermal Holding in Two HSLA Steels

2021 ◽  
Vol 52 (5) ◽  
pp. 1812-1825
Author(s):  
Sen Lin ◽  
Ulrika Borggren ◽  
Andreas Stark ◽  
Annika Borgenstam ◽  
Wangzhong Mu ◽  
...  
Keyword(s):  
Isothermal Holding ◽  
Weight Percent ◽  
High Energy ◽  
Decomposition Kinetics ◽  
Bainitic Transformation ◽  
Austenite Decomposition ◽  
X Ray Diffraction ◽  
Rapid Cooling ◽  
X Ray

AbstractIn-situ high-energy X-ray diffraction experiments with high temporal resolution during rapid cooling (280 °C s−1) and isothermal heat treatments (at 450 °C, 500 °C, and 550 °C for 30 minutes) were performed to study austenite decomposition in two commercial high-strength low-alloy steels. The rapid phase transformations occurring in these types of steels are investigated for the first time in-situ, aiding a detailed analysis of the austenite decomposition kinetics. For the low hardenability steel with main composition Fe-0.08C-1.7Mn-0.403Si-0.303Cr in weight percent, austenite decomposition to polygonal ferrite and bainite occurs already during the initial cooling. However, for the high hardenability steel with main composition Fe-0.08C-1.79Mn-0.182Si-0.757Cr-0.094Mo in weight percent, the austenite decomposition kinetics is retarded, chiefly by the Mo addition, and therefore mainly bainitic transformation occurs during isothermal holding; the bainitic transformation rate at the isothermal holding is clearly enhanced by lowered temperature from 550 °C to 500 °C and 450 °C. During prolonged isothermal holding, carbide formation leads to decreased austenite carbon content and promotes continued bainitic ferrite formation. Moreover, at prolonged isothermal holding at higher temperatures some degenerate pearlite form.

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