X Ray Topography Study of Deformed Crystal-Quasicrystal Composites of Al Cu Fe Alloy

2010 ◽  
Vol 163 ◽  
pp. 278-281 ◽  
Author(s):  
Włodzimierz Bogdanowicz ◽  
Jacek Krawczyk
Keyword(s):  
Optical Microscopy ◽  
Phase Analysis ◽  
Misorientation Angle ◽  
Tensile Strain ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
The Matrix ◽  
Powder Phase

Crystal-quasicrystal columnar composites (CQ composites) of Al Cu Fe alloy subject to tensile strain at room temperature were studied by the reflective X ray topography. In those composites singlecrystalline β phase occurred as the matrix and rods consisting of quasicrystalline ψ phase and crystalline λ phase as the reinforcement. X-ray topograms of plate like composite specimens were obtained using reflexes of singlecrystalline matrix. It has been found that at strains ε up to 0.33% in a linear range of stress strain σ(ε) relationship the topograms remain unchanged. Instead, at ε higher than 0.33% significant contract changes have been observed in some areas of topograms. It has been determined that at ε higher than 0.33% the components of misorientation angle of those areas increase with increasing strain. Methods of powder phase analysis, metallographic examinations by means of optical microscopy methods and X-ray diffraction topography methods were used.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

Macro-and Microstrain Relaxation in Annealed Ag Films During Ageing at Room Temperature

1997 ◽  
Vol 505 ◽  
Author(s):  
R. C. Currie ◽  
R. Delhez ◽  
E. J. Mitiemeijer
Keyword(s):  
Room Temperature ◽  
Strain Relaxation ◽  
Diffraction Line ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Diffraction Line Profile ◽  
The Matrix ◽  
Profile Position

ABSTRACTThe relaxation of thermally induced strain in 500 nm thick polycrystalline Ag layers electron-beam deposited onto Si wafers was traced during ageing at room temperature. The layers consisted predominantly of matrix crystallites with {111} planes parallel to the surface and twin crystallites with {51 l} planes parallel to the surface. The macrostrain in the plane of the layer was determined from the X-ray diffraction line-profile position and the microstrain from the diffraction-line broadening. The residual macrostress relaxed from 160 MPa to 30 MPa in the matrix crystallites and from 170 MPa to 50 MPa in the twin crystallites. Simultaneously with the decrease in macrostress the microstrain decreases significantly for both texture fractions. The strain relaxation behaviour is governed by movement and subsequent annihilation of defects in the layer.

X-ray study of the α–β transformation of berlinite (AlPO4)

1976 ◽  
Vol 54 (6) ◽  
pp. 638-647 ◽  
Author(s):  
H. N. Ng ◽  
C. Calvo
Keyword(s):  
Room Temperature ◽  
Translational Motion ◽  
Fold Axis ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Atomic Displacements ◽  
Β Phase ◽  
Four Corners ◽  
Dauphiné Twinning

The α–β transformation of berlinite (AlPO4) at 586 °C was studied by X-ray diffraction. Atomic displacements were obtained from results of least-squares refinement of data taken between room temperature and 600 °C using reflections whose intensity is unaffected by Dauphiné twinning. The results suggest a rotational motion of the PO4 and AlO4 tetrahedra around the two-fold axis together with a translational motion along the same axis as the transition is approached from below. The vibrational amplitudes of the atoms increase with temperature and have exceeded half of the separation between Dauphiné twin-related configurations at 500 °C. The final β-phase configuration is not achieved by this twinning due to the mismatch of the two configurational potential minima in the a direction. Analysis of the intensity vs. temperature data favours a single minimum model for the β phase configuration over an order–disorder model. The β-AlPO4 structure consists of alternate PO4 and AlO4 tetrahedra sharing all four corners with P—O and Al—O distances 1.505 and 1.694 Å respectively. The results are correlated with those obtained from temperature dependent studies by Raman scattering and by EPR on Fe3+-doped AlPO4.

scholarly journals Simulation Study of Helium Effect on the Microstructure of Nanocrystalline Body-Centered Cubic Iron

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 91 ◽  
Author(s):  
Chunping Xu ◽  
Wenjun Wang
Keyword(s):  
Lattice Constant ◽  
Tensile Strain ◽  
Room Temperature ◽  
Md Simulation ◽  
Uniaxial Tensile ◽  
Body Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Swelling Rate ◽  
Simulation Results

Helium (He) effect on the microstructure of nanocrystalline body-centered cubic iron (BCC-Fe) was studied through Molecular Dynamics (MD) simulation and simulated X-ray Diffraction (XRD). The crack generation and the change of lattice constant were investigated under a uniaxial tensile strain at room temperature to explore the roles of He concentration and distribution played in the degradation of mechanical properties. The simulation results show that the expansion of the lattice constant decreases and the swelling rate increases while the He in the BCC region diffuses into the grain boundary (GB) region. The mechanical property of nanocrystalline BCC-Fe shows He concentration and distribution dependence, and the existence of He in GB is found to benefit the generation and growth of cracks and to affect the strength of GB during loading. It is observed that the reduction of tensile stress contributed by GB He is more obvious than that contributed by grain interior He.

scholarly journals Polar and non-polar structures of NH4TiOF3

2019 ◽  
Vol 52 (1) ◽  
pp. 23-26
Author(s):  
O. Boytsova ◽  
I. Dovgaliuk ◽  
D. Chernyshov ◽  
A. Eliseev ◽  
P. O'Brien ◽  
...  
Keyword(s):  
Room Temperature ◽  
Phase 1 ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Starting Compound ◽  
Different Temperatures ◽  
Fourfold Axis

Ammonium oxofluorotitanate, NH4TiOF3, is probably the best known precursor for the synthesis of anatase mesocrystals. Transformation of NH4TiOF3 into TiO2 through thermal decomposition, accompanied by hydrolysis, preserves some structural features of the precursor. Currently, any discussion of the mechanism of this transformation is difficult, as the exact crystal structure of the starting compound is not available and no intermediate structures are known. This article describes the outcome of single-crystal and powder X-ray diffraction studies, revealing the existence of two polymorphs of the parent NH4TiOF3 at different temperatures. A second-order phase transition from the polar Pca21 α phase (1), stable at room temperature, to the Pma2 β phase (2) above ∼433 K has been demonstrated. The direction of the pseudo-fourfold axis in NH4TiOF3 coincides with the orientation of the fourfold axis of anatase mesocrystals, consistent with a topotactical transformation.

scholarly journals Investigation of Y2.1Er0.9(ScxGa1−x)5O12 Matrix Components on the Spectral Properties around 3.0 μm by Micro-Pulling-Down Method

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 138
Author(s):  
Zhijiang Che ◽  
Jian Zhang ◽  
Baiyi Wu ◽  
Qiangqiang Hu ◽  
Wenxiang Mu ◽  
...  
Keyword(s):  
Fluorescence Spectra ◽  
Room Temperature ◽  
Lattice Vibration ◽  
Emission Spectra ◽  
X Ray Diffraction ◽  
Mid Infrared ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
The Matrix ◽  
Crystal Fibers

Single crystal fibers of 30% Er3+-doped compound of Y3(ScxGa1−x)5O12 have been grown by using the micro-pulling down (μ-PD) technique successfully. Our main purpose is to tune the fluorescence properties by adjusting the ratios of Sc3+ and Ga3+ ions inside the matrix crystals. The crystal structures of the series compounds were measured and analyzed through X-ray diffraction (XRD) measurements. The components and doping elements distributions were measured by the X-ray Fluorescence spectrometry and electron-probe microanalyzer. The absorption and mid-infrared fluorescence spectra, including the fluorescent lifetime of Er3+:4I13/2 and 4I11/2 levels were measured and compared systematically at room temperature. Spectral analysis indicated that the fluorescent lifetime of Er3+:4I13/2 tended to shorten and the emission spectra began to show a red shift when the proportion of YSG increased in the compound. Furthermore, the Raman spectra were measured to reveal the variations of lattice vibration and phonon energy.

Microstructure Characteristics of Fe-xCr-C Hardfacing Alloys

2012 ◽  
Vol 472-475 ◽  
pp. 165-168
Author(s):  
Lin Zong ◽  
Zheng Jun Liu
Keyword(s):  
Solid Solution ◽  
Optical Microscopy ◽  
Arc Welding ◽  
Room Temperature ◽  
Gas Tungsten Arc Welding ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Gas Tungsten Arc ◽  
Gtaw Process

A series of Fe-xCr-C hardfacing alloys were successfully fabricated on a substrate of 20g steel by gas tungsten arc welding (GTAW) process. These claddings were disigned to observe hypoeutectic, near-eutectic, and hypereutectic structures with various Cr3C2 and M7C3 carbides at room temperature. According to X-ray diffraction(XRD) and optical microscopy (OM), the hypoeutectic and eutectic composites include the Fe-Cr solid solution(α+A) and Cr3C2 carbides. Hypereutectic structures consist of α+A+M+M7C3 respectively. The cladding of hypereutectic microstructure with great amounts of primary M7C3 carbides had the highest hardness of the all conditions.

Phase Constituents of Ti-Cr-Au and Ti-Cr-Au-Zr Alloy Systems

2010 ◽  
Vol 654-656 ◽  
pp. 2122-2125 ◽  
Author(s):  
Yuri Shinohara ◽  
Takuya Ishigaki ◽  
Tomonari Inamura ◽  
Hiroyasu Kanetaka ◽  
Shuichi Miyazaki ◽  
...  
Keyword(s):  
Ternary System ◽  
Diffraction Analysis ◽  
Optical Microscopy ◽  
Laves Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quaternary Systems ◽  
Β Phase ◽  
Zr Alloy ◽  
Alloy Systems

The phase constituents of the Ti-Cr-Au ternary and Ti-Cr-Au-Zr quaternary systems were investigated using X-ray diffraction analysis and optical microscopy. The composition ranges were 3~10mol%Cr and 0~8mol%Au for the ternary system, and 0~42mol%Zr were added to Ti-5mol%Cr-4mol%Au. It was found that the β phase was stabilized by the addition of Cr and Zr, and that A15-type Ti3Au was formed when the Au content was 6mol% or higher. Besides, C14 Laves phase similar to Zr33Ti40Au27 was recognized in Ti-5mol%Cr-4mol%Au-42mol%Zr.

Tribological behaviour of AZ91D/ultra-high-temperature ceramic composites at room and elevated temperatures

2021 ◽  
pp. 135065012110100
Author(s):  
KT Sunu Surendran ◽  
A Gnanavelbabu
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Wear Test ◽  
X Ray Diffraction ◽  
Tribological Behaviour ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron ◽  
Ultra High Temperature

In this research work, the tribological behaviour of an AZ91D alloy and its composites reinforced with different titanium-based ultra-high-temperature ceramic particulates was investigated. Titanium-based ultra-high-temperature ceramic materials (5 wt%) such as titanium carbide, titanium boride and titanium nitride was used for the fabrication of three different composites, namely ATC, ATB and ATN, respectively. The proposed composites were prepared using a novel ultrasonic treatment-assisted stir-squeeze casting technique. Material characterization was performed using scanning electron microscopy and X-ray diffraction techniques. The porosity and hardness of the composites were determined prior to the wear test. In the pin-on-disc tribometer, the wear test was carried out at room temperature by varying the normal load (12.5–50 N) and the sliding speed (0.25–1 m/s). In addition, at a temperature of up to 200 °C, the tribological behaviour of the composites was assessed. The homogeneous distribution of ultra-high-temperature ceramic particles in the matrix was confirmed by the analysis of the microstructure using scanning electron microscopy images. The X-ray diffraction results showed that the reinforcement materials in the matrix were thermally stable. The hardness of the ATC, ATB and ATN was improved by approximately 31%, 33.8% and 29.6%, respectively. In comparison, at all wear testing conditions, ATB demonstrated superior tribological performance, while the performance of ATN was poor and ATC was moderate. Abrasion, oxidation and delamination were the wear mechanisms at room temperature. At elevated temperatures, oxidation, delamination, thermal softening and plastic deformation wear mechanisms were significant..

Alignment Behaviors on ITO Glass and Electrical Properties of Triphenylene Compound

2010 ◽  
Vol 428-429 ◽  
pp. 267-271
Author(s):  
Chun Xiu Zhang ◽  
Zhi Qun He ◽  
Jia Ling Pu ◽  
Yu Ning ◽  
Hao Wu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Electrical Properties ◽  
Scanning Electron Microscope ◽  
Optical Microscopy ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ito Glass ◽  
Micro Structures ◽  
Scanning Electron

The alignment of 2, 3, 6, 7, 10, 11-hexapentaloxy triphenylene (HAT5) on ITO glasses was investigated by polarizing optical microscopy, differential scanning calorimeter, X-ray diffraction and scan scanning electron microscope in this study. The results showed that the alignment of 2, 3, 6, 7, 10, 11-hexapentaloxy triphenylene can be fixed at room temperature by heating the sample to the isotropic temperature and annealing at 100°C overnight and then cooling slowly back to room temperature; the ordered arrangements of the micro structures are disconnected. The disconnection of the microstructure and the size of columnar assemblies can also be confirmed from the SEM observations.

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