Effect of Hydrogen Redistribution during Aging on the Martensitic Transformation and Superelasticity of Nanocrystalline TiNi Alloy

2019 ◽  
Vol 31 ◽  
pp. 30-34 ◽  
Author(s):  
Anatolii Baturin ◽  
Alexander Lotkov ◽  
Victor Grishkov ◽  
Ivan Rodionov ◽  
Dorzhima Zhapova
Keyword(s):  
Room Temperature ◽  
Structural Phase ◽  
Tini Alloy ◽  
Hydrogen Effect ◽  
Ultrafine Grained ◽  
Electrolytic Hydrogenation ◽  
Redistribution Of Hydrogen ◽  
B2 Structure ◽  
Structural Phase Transformations

The paper presents the results of a study the hydrogen effect on the structural-phase transformations and the superelasticity in binary ultrafine-grained (UFG) TiNi based alloy after diffusion redistribution hydrogen as a result of aging at room temperature. The redistribution of hydrogen in the process of long-term aging after electrolytic hydrogenation of UFG wire specimens the Ti49,1Ni50,9(at.%) stabilizes the B2 structure. Superelasticity in samples aged at room temperature after hydrogenation is significantly deteriorated.

Enhancement of the CMR Effect Near Room Temperature by Defects and Structural Transitions in La1−x−yCaxSryMnO3

1999 ◽  
Vol 602 ◽  
Author(s):  
S. Kolesnik ◽  
B. Dabrowski ◽  
Z. Bukowski ◽  
J. Mais
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Structural Phase ◽  
Zero Magnetic Field ◽  
Ferromagnetic Transition ◽  
Spin Lattice ◽  
Preparation Conditions ◽  
Close Proximity ◽  
Selection Of ◽  
Structural Phase Transformations

AbstractWe have studied magnetoresistance of a series of La1−xSrxMnO3 and La1−x−yCaxSryMnO3 samples, for which structural and ferromagnetic transformation temperatures are in close proximity. On cooling in zero magnetic field, we observe a rapid increase of resistivity just above TC for La1−xSrxMnO3 samples with x < 0.1425 and x ≤ 0.1725 due to the O*-O' and R-O* - structural phase transformations, respectively. This increase is followed by a rapid decrease due to the ferromagnetic transition. The applied magnetic field significantly shifts the ferromagnetic transition to higher temperatures and suppresses the structure-related resistivity increase. We show that a combination of structural and ferromagnetic transitions gives rise to an enhancement of the negative magnetoresistance due to strong spin-lattice coupling. By choosing a proper composition, the enhancement can be optimized to appear in relatively low magnetic fields. A proper selection of Sr and Ca contents in La1−x−yCaxSryMnO3 and preparation conditions leads to an enhancement of the magnetoresistance effect at room temperature.

On the Dynamic Superplasticity

2016 ◽  
Vol 879 ◽  
pp. 960-965 ◽  
Author(s):  
Daria Kitaeva ◽  
Georgii Kodzhaspirov ◽  
Yakov Rudaev
Keyword(s):  
Polycrystalline Material ◽  
Structural Phase ◽  
Structural Condition ◽  
Dissipative Structures ◽  
Nonequilibrium Systems ◽  
Strain Rates ◽  
Structural Superplasticity ◽  
Ultrafine Grained ◽  
Deformation Processes ◽  
Structural Phase Transformations

Superplasticity is considered as a special state of the polycrystalline material plastically deformed at the low level of the stress with the retaining of the ultrafine-grained structure – structural superplasticity received at the previous stage or arised during hot deformation independently from the initial grain size – dynamic superplasticity. For realization of the dynamic superplasticity it has to substitute an initial structural condition of material another, allowed to realize a superplasticity. The mentioned above changes are caused by the conforms of the proper strain rates and structural (phase) transformations of the evolutionary type in the open nonequilibrium systems. It is proposed an approach applying to the modelling of the deformation processes at the superplastic flow of commercial aluminum alloys taking into account the boundary regions in the framework the theory of self-organization of dissipative structures. An examples of the theoretical and experimental data correlation are given.

Convergent-beam characterization of some oxides which undergo structural phase transformations

1987 ◽  
Vol 45 ◽  
pp. 20-23
Author(s):  
M. Tanaka
Keyword(s):  
Phase Transformations ◽  
Room Temperature ◽  
Materials Science ◽  
Present Report ◽  
Structural Phase ◽  
Crystal Defects ◽  
Temperature Phase ◽  
Space Group ◽  
Convergent Beam ◽  
Structural Phase Transformations

We have been concerned with the development of convergent-beam electron diffraction (CBED) techniques and their application to materials science. Our effort is now concentrated to identify the nature of crystal defects. Our application has been focussed on materials most of which undergo structural phase transformations: NdNbO4, La2Ti2O7, Sr2(Ta1-xNbx)2O7, Fe3O4, PbZrO3, PbZrO0-7Ti0.3O3, SrTiO3, BaPb1-xBixO3, hex.BaTiO3, Bi2.5Na0.5Nb2O9, MgAl2O4, MnSi, TaS3, NbS3+x, Mo2S3. In the present report, the results on four oxides will be reviewed.a) La2Ti2O7Gasperin determined the space group of the room temperature phase to be P21, but Scheunemann and Miüller-Buschbaum reported its space group to be Pna21. Ishizawa et al. studied the phase transformation between room temperature and 1173 K using X-ray diffraction. They determined the space group of the room temperature phase to be P21 and found the presence of twin domains.

Crystal Structure Analysis of the Mg2Si1-xSnx System Having Potential Thermoelectric Properties at High Temperature

2011 ◽  
Vol 170 ◽  
pp. 253-258 ◽  
Author(s):  
D. Boudemagh ◽  
Daniel Fruchart ◽  
R. Haettel ◽  
El Kebir Hlil ◽  
A. Lacoste ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Phase ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laves Phases ◽  
X Ray ◽  
Frequency Coupling ◽  
Xrd Patterns ◽  
Structural Phase Transformations

Laves phases of C15 type of the system Mg2Si1-xSnx with x = 0, 0.4, 0.6 and 1 were synthesized in polycrystalline state in tantalum ampoule heated by high frequency coupling. The as-cast materials were analysed first at room temperature by X-ray diffraction (XRD). Systematically, XRD patterns were recorded up to 700 °C and Differential Scanning Calorimetry analysis was performed up to 1200°C to control the chemical and structural phase transformations. From these experiments, a C15 to C36 structure transformation was pointed out around 600°C in Mg2Si1-xSnx.solid solutions.

scholarly journals Preparation, composition, structure and properties of mechanically alloyed heat‑resistant steels

2021 ◽  
pp. 70-78
Author(s):  
F. G. Lovshenko ◽  
E. I. Marukovich ◽  
I. A. Lozikov ◽  
A. I. Khabibulin
Keyword(s):  
Structural Phase ◽  
Scientific Basis ◽  
Structure And Properties ◽  
Mechanically Alloyed ◽  
Thermally Activated ◽  
Heat Resistant ◽  
Composition Structure ◽  
Heat Resistant Steels ◽  
Structural Phase Transformations

Despite a significant amount of work in the field of mechanically doped alloys and, above all, based on aluminum and copper, research aimed at creating mechanically doped alloys is extremely limited. In this regard, the following work aimed at to establishing the regularities of the formation of the phase composition, structure, and properties in the implementation of the technology for obtaining mechanically doped heat‑resistant steels, is important and relevant.The basis for the development of mechanically doped alloys were the results of long‑term research carried out at the Belarusian‑Russian University and aimed at studying mechanically and thermally activated structural phase transformations taking place at all the technological stages of obtaining mechanically doped metal alloys. In this article, in a generalized form the final research results are presented, revealing the patterns of these transformations, which are a reliable scientific basis for the creation of mechanically doped complex‑hardened heat‑resistant steels.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Water repellent room temperature vulcanized silicone for enhancing the long-term stability of perovskite solar cells

Solar Energy ◽  
2021 ◽  
Vol 218 ◽  
pp. 28-34
Author(s):  
Mahmoud Samadpour ◽  
Mahsa Heydari ◽  
Mahdi Mohammadi ◽  
Parisa Parand ◽  
Nima Taghavinia
Keyword(s):  
Solar Cells ◽  
Room Temperature ◽  
Perovskite Solar Cells ◽  
Water Repellent ◽  
Term Stability ◽  
Long Term Stability

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

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