0000000000020927
AUTHOR
Ryszard Pietrzak
Investigation of corrosion defects in titanium by positron annihilation
Abstract The positron annihilation method was used to study the formation of defects in titanium samples during their corrosion in the vapor of a 3% HCl solution. In particular, the distribution of defects depending on the distance from the corroding surface and the impact of an external magnetic field on the concentration of vacancies forming during the corrosion of titanium layers close to the surface were determined.
Influence of the external stretching on hydrogen electromigration in palladium
Abstract Electromigration and diffusion of hydrogen in palladium depending on unit elongation were investigated. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen, which diffuses in a gradient of electric field. In order to effectively explain the obtained results, a theoretical model was elaborated. It assumed the existence of the following two fluxes of hydrogen in the stretched metal: • Ji—of migration, according to the interstitial mechanism, and • Ji-d—of migration, according to the interstitial-defective mechanism. Dependence of effective valences and diffusion coefficients for both mechanisms of transportation were determine…
Effect of magnetic field on the corrosion of iron and St20 steel as studied by positron annihilation
Lifetime spectra of positron annihilation in iron and St20 steel corroded in the water solution of HCl and in vapour above its surface have been investigated with emphasis on the effect of corrosion time and environment (solution or vapour) as well as of the presence and orientation of the magnetic field on the measured positron annihilation parameters. All the registered positron lifetime spectra consist of two components. For corroded samples the intensities of the two components as well as the corresponding values of the mean positron lifetime, differ from those for uncorroded material. The corrosion-induced changes in the positron annihilation parameters depend on the corrosion environm…
The Effect of Impact Pressure on Positron Lifetime in Ultra High Molecular Weight Polyethylene (PE-UHMW)Chirulen®1120
The paper presents the results of investigations of the effect of impact pressure (in the range of both elastic and plastic deformations) on the parameters of the positron lifetime spectra in PE-UMHW polymer known under the trade mark Chirulen1120. The changes in the long-living component of the positron lifetime spectrum, connected with the annihilation of o-Ps in the pick-off process, are analyzed in dependence on the impact energy. The impact duration in the Charpy’s tests depending on the impact energy was measured, too. The dependencies of the radius of the volume of empty spaces in which the positronium annihilates, on the impact pressure were determined applying the Eldrup-Tao model.
Influence of crystal defects on the electromigration of the hydrogen in palladium
Abstract Electromigration and diffusion of hydrogen in palladium defected through quenching to liquid nitrogen temperature were investigated. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen which diffuses in a gradient of electric field. In order to effectively explain the obtained results, a theoretical model was elaborated. It assumed the existence of the following two fluxes of hydrogen in the quenched metal: • Ji—of migration, according to the interstitial mechanism, and • Ji–d—of migration, according to the interstitial-defective mechanism. Dependence of effective valences and diffusion coefficients for both mechanisms of tr…
Investigation of diffusion and migration of hydrogen, deuterium and tritium in palladium in a Hall field
Abstract The migration of hydrogen, deuterium and tritium in palladium in a Hall field at 343 K was investigated, using resistance and isotope methods. It was found that all isotopes of hydrogen migrate towards the negative Hall electrode. The effective charges of the migration in a Hall field are 194 ±3 e for hydrogen and 464± 5 e for deuterium and tritium. The results obtained confirm predictions of a tentative model based on the electron-balistic theories of migration in a Hall field.
Influence of external stretching on hydrogen electromigration in Pd and PdCu, PdAg alloys
Influence of external stretching of Pd and Pd77Cu23 and Pd77Ag23 alloys on hydrogen electromigration in these systems was investigated. The electro-resistivity method was applied in the investigations. It was found that in order to furnish a full description of the kinetics and dynamics transport of hydrogen in the externally applied electric field to samples in the state of elastic and plastic stretching, it is not sufficient to provide a functional dependence of two commonly used parameters (diffusion coefficient D and effective valence Zeff) on degree of deformation. To describe the electromigration in these conditions a mathematical model was applied, which assumes the existence of two …
The electromigration and diffusion of hydrogen in molybdenum
Abstract The electromigration and diffusion of hydrogen atoms in molybdenum were investigated using the resistance method in the temperature range 293–773 K. The following dependence of the diffusion coefficient D and electrical mobility vE on temperature were obtained: D = (5.3 ± 1.53) × 10 −10 exp {− (0.8 ± 0.01) eV kT } { m 2 s −1 } v E = (1.24 ± 0.19) × 10 −8 exp {− (0.9 ± 0.01) eV kT }{ m 2 ( V s ) −1 } . The hydrogen migrates towards the cathode and the effective valency grows with temperature, fulfilling the relation Z eff = (1.42 ± 0.03) − (5.0 ± 0.2) × 10 −8 (Ω m ) ρ ; where ρ is the specific electric resistance.
Effect of magnetic field on the corrosion of iron and St20 steel as studied by positron annihilation [Phys. Status Solidi B 247(7), 1822-1828 (2010)]
We alert our readers that part of the contents of the article by R. Pietrzak and R. Szatanik, Phys. Status Solidi B 247, 1822 (2010) [DOI 10.1002/pssb.200945124] was already published in an earlier conference proceedings paper by the same authors which appeared in Nukleonika 55, 31 (2010).