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1
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Melting Process of the Sn-45 wt.% In and Sn-77 wt.% In Alloys as Viewed by Positron Annihilation

100%
Rudzińska W., Szuszkiewicz M.
Acta Physica Polonica A
|
2006
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vol. 110
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issue 5
701-708
EN
The temperature dependences of the positron annihilation parameters F and R were determined for Sn-45 wt.% In and Sn-77 wt.% In alloys. The obtained results enabled to verify the vacancy and the quasicrystalline models of the melting process. It was found that for metals transforming into the liquid state from the structures different than the close packed structure, the melting transition are hardly explainable in terms of the vacancy model of melting. The strong trapping of positrons in metallic liquids is an indication of the presence of microvoids (vacancy clusters) or microcrystals containing defects more immense than vacancies. The share of these positron trapping centers in the volume of metallic liquids is constant or decreases with increasing temperature. The obtained results demonstrate the particular applicability of the positron annihilation method for studies of defect kinetics in metallic liquids.
2
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Positron Annihilation in Pure and Hydrogenated Palladium Deformed by Uniaxial Tension

81%
Rudzińska W., Pająk J., Szymański C., Szatanik R.
Acta Physica Polonica A
|
2001
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vol. 99
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issue 3-4
479-486
EN
Angular distributions of the positron annihilation quanta were measured for pure and hydrogenated palladium samples deformed by uniaxial tension up to different deformation degrees. The relative difference curves, and the values of the R parameter characterizing the dimensions of defects trapping the positrons, were determined. It was found that for relative elongations ranging from 1.9 to 3.5%, in both the pure and hydrogenated palladium, the positrons are trapped in defects larger than vacancy clusters. The values of the R parameter for pure palladium samples elongated up to 0.39, 0.77, and 1.5% indicate a dominant role of smaller defects, like the vacancy clusters.
3
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Investigation of the Solid-Liquid Phase Transition for SnIn Alloys by the Positron Annihilation Method

81%
Chabik S., Rudzińska W., Szuszkiewicz M., Szymański C.
Acta Physica Polonica A
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1993
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vol. 83
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issue 3
261-265
EN
The monovacancy formation energy in Sn-17 wt.% In and Sn-32 wt.% In was determined on the basis of the temperature dependence of the peak counting rate for these alloys. A sudden increase in the counting rate was observed between solidus and liquidus temperature. This phenomenon is connected with the formation of large defects acting as positron traps.
4
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Investigation, of Solid-Liquid Phase Transition for Sn-54wt%In Alloy by Positron Anihilation Spectroscopy

81%
Chabik S., Szuszkiewicza M., Rudzińska W.
Acta Physica Polonica A
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1995
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vol. 88
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issue 1
97-101
EN
The peak coincidence counting rate F(T) was measured for Sn-54wt%In alloy at the temperature range from room temperature to 400°C. It was observed that for both heating and cooling run, F(Τ) parameter changes in the liquid phase. These changes were related to disintegration of SnII microcrystals. From a simple trapping model the defect disintegration enthalpy, H_{1}, was calculated. For heating and cooling run, the value of H_{1} was 0.53 ± 0.03 eV and 0.67 ± 0.07 eV, respectively. For well-annealed and cold rolled samples we find only one component, equal 200 ps, in the lifetime spectrum.
5
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Positron Annihilation in Steel Samples Deformed by Uniaxial Tension

81%
Rudzińska W., Szuszkiewicz M., Bujnarowski G., Kluza A.
Acta Physica Polonica A
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2008
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vol. 113
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issue 5
1507-1510
EN
Angular distributions of the positron annihilation quanta were measured for steel ST2 SAL samples deformed by uniaxial tension up to different deformation degrees. The dependences of the S parameter on the relative elongation of the samples are presented. The positron annihilation data for steel are compared with the results obtained previously for polycrystalline iron samples deformed by uniaxial tension up to different deformation degrees in the proportionality and limited proportionality regions.
6
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Positron Annihilation in Solid and Liquid Bi_{40}Sn_{60} Alloy

81%
Chabik S., Rudzińska W., Szuszkiewicz M., Szymański C.
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vol. 95
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issue 4
479-482
EN
The peak counting rate, F(T), for Bi_{40}Sn_{60} alloy in the temperature range from room temperature to 400°C was measured in three consecutive heating-cooling runs. Significant changes in F(T) were observed in the temperature interval between the solidus and liquidus temperature. The magnitude of these anomalies systematically diminishes in consecutive heating-cooling runs. Noticeable changes of values of F(T) parameter in the liquid alloy were observed, too. These effects were connected with trapping of positrons at the grain boundaries-defects and in the short-range ordered regions in the liquid alloy. Also microscopic structure of sample before and after measurements cycles was observed.
7
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Positron Annihilation in Defected Monocrystalline Gold Samples

81%
Pająk J., Rudzińska W., Szuszkiewicz M., Garłowska M.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
848-851
EN
Angular distribution of the positron annihilation quanta was measured for monocrystalline gold samples, oriented in (110) and (111) directions. The samples were deformed by elongation for different deformation degrees. The S and W parameters as a function of deformation degree of the sample were determined. It was found that the dynamics of the dislocations and vacancy generation during the sliding of some crystallographic planes, depends on the crystallographic direction.
8
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Investigation of the Absorption of Annihilation Quanta in Solid and Liquid Ga and BiSn Alloy

81%
Kluza A., Rudzińska W., Szuszkiewicz M.
Acta Physica Polonica A
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2001
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vol. 99
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issue 3-4
407-413
EN
Absorption of positron annihilation quanta in Ga and Bi_{40}Sn_{60} alloy in the solid and the liquid phase was investigated. It was found that the mechanism of absorption of annihilation quanta changes on passing from the solid to the liquid state. Results of measurements for Ga and Bi_{40}Sn_{60} alloy show that for metals changing their density at the melting point the photopeak profiles are modified: their centers of gravity in liquid phase are displaced with respect to those in the solid phase and the number of counts under the photopeak changes, too.
9
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Positron Annihilation in Polycrystalline Metals Deformed by Uniaxial Tension

71%
Rudzińska W., Pająk J., Szuszkiewicz M., Bujnarowski G., Kluza A.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
857-863
EN
Angular distributions of the positron annihilation quanta were measured for polycrystalline samples deformed by uniaxial tension up to different deformation degrees. The S parameter as a function of the W parameter was determined. The data obtained for samples elongated up to different elongation degrees indicate that in the proportionality and limited proportionality regions the changes in the physical properties of samples are governed mainly by generation of vacancies and formation and kinetics of transformations of vacancy clusters occurring first of all on the grains of monocrystallites. In the region of plastic deformations the dominant defects are dislocations and vacancies and their aggregates generated due to the formation and movement of the dislocation of the primary and secondary slip. The positron annihilation data are corroborated by the results of the resistometric and tensometric measurements in the proportionality and limited proportionality regions.
10
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Positron Annihilation in Metals Defected by Action of the Tensile Force

71%
Rudzińska W., Pająk J., Szuszkiewicz M., Bujnarowski G., Kluza A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
691-699
EN
Results of experimental investigations of uniaxially elongated mono- and polycrystalline samples of several metals (Fe, Ta, Pd, Ag, and Au), performed using the positron annihilation methods, are reviewed. The dependences of the S-parameters and positron lifetimes on the relative elongation of the samples were presented. The data obtained for polycrystalline samples indicate that in the proportionality and limited proportionality regions the changes in the physical properties are governed mainly by generation of vacancies and by kinetics of formation and transformations of vacancy clusters occurring first of all on the grain boundaries of monocrystallites. In the region of plastic deformations the dominant defects are dislocations and vacancies and their aggregates generated due to the formation and movement of the dislocations of the primary and secondary slip. In the case of monocrystalline samples it was found that the dynamics of the dislocations and vacancy generation during the sliding of some crystallographic planes depends on the crystallographic direction.
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