Search

Your search keyword '"Lelątko, Józef"' showing total 105 results
Start Over Author "Lelątko, Józef"
105 results on '"Lelątko, Józef"'

22. Influence of structural changes of Co78Si9B13 metallic glass on magnetic properties

Author

Jakubczyk, Ewa, Lelątko, Józef, Pawlik, Katarzyna, and Przybył, Anna

Subjects
crystallization, metallic glass, coercivity
Abstract

The primary crystallization of Co78Si9B13 metallic glass starts at 648 K and as a consequence of this the ε-Co(Si) phase with needle morphology is created. The second stage of crystallization (at 773 K) is the eutectic and as a result of this α-Co(Si) and boron phases: (Co,Si)3B, (Co,Si)2B are formed. The crystallites of these phases have layer morphology. These characteristic morphologies in the first and second stages lead to the increase in coercivity.

Published
2009

23. Ordering of [alpha]-FeCo phase in the nanocrystalline Fe83-xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys

Author

Zbroszczyk, Józef, Młyńczyk, Alina, Olszewski, Jacek, Ciurzyńska, Wanda, Wysłocki, Bolesław, Perduta, Kamila, Lelątko, Józef, and Nabiałek, Marcin

Subjects
nanocrystalline alloys, Mössbauer spectroscopy, microstructure, ordering
Abstract

The microstructure and ordering of α-FeCo phase of the nanocrystalline Fe83−xCoxNb3B13Cu1 (x = 6, 25 or 41.5) alloys were investigated. We have stated that α-FeCo phase is atomically ordered in the Fe83−xCoxNb3B13Cu1 (x = 25 or 41.5) samples crystallized by the heat treatment in a furnace. However, after flash annealing (by current or laser) that phase is disordered. Moreover, we have found that Co concentration in the crystalline α-FeCo phase strongly depends on Co content in the as-quenched ribbons. The annealing conditions influence also the grain diameter of the crystalline phase. In the nanocrystalline alloys obtained by a flash annealing of the amorphous ribbons finer grains are present.

Published
2007

24. Mossbauer studies of structure relaxations near nanocrystallization region in amorphous Fe90Zr7B3 alloy

Author

Świerczek, Jan and Lelątko, Józef

Subjects
Condensed Matter::Materials Science, amorphous structure relaxation, Mössbauer spectroscopy, nanocrystallization
Abstract

Transmission Mössbauer spectra and high-resolution electron microscopy investigations for amorphous Fe90Zr7B3 alloy in the as-quenched state and after annealing in vacuum at temperatures 673, 723 and 743 K have been performed. In the as-quenched state the microstructure reveals the presence of medium range order BCC- or FCC-like structure regions 1−3 nm in size which grow during annealing at 673 K being the nuclei of grains of α-Fe phase. After annealing at 723 K for 1 h, the grains 16 nm in diameter and with the average distance of 110 nm between them are embedded in the paramagnetic amorphous matrix. This distance is large enough to prevent magnetic interaction between the grains, and superparamagnetic behavior is observed. After longer annealing at 723 K and at 743 K, the Mössbauer spectra show a crystalline component of the α-Fe phase with the inhomogeneous amorphous matrix consisting of paraand ferromagnetic phases. The hyperfine induction of the crystalline phase slightly increases with time and annealing temperature which is ascribed to the faster diffusion of atoms.

Published
2007

25. Nanocrystallization studies of rapidly quenched Fe85.4-xCoxZr6.8-yNbyB6.8Cu1 (x=0 or 42.7, y=0 or 1) alloys

Author

Olszewski, Jacek, Zbroszczyk, Józef, Ciurzyńska, Wanda, Fukunaga, H., Wysłocki, Bolesław, Perduta, Kamila, Łukiewska, Agnieszka, Młyńczyk, Alina, Lelątko, Józef, and Świerczek, Jan

Subjects
nanocrystalline Fe-Co alloys, Mössbauer spectra
Abstract

The microstructure of amorphous and nanocrystalline Fe42.7Co42.7Zr6.8−xNbxB6.8Cu1 (x = 0 or 1) alloys was investigated. We have stated that the nanocrystalline samples consist of the crystalline α-FeCo grains about 8 nm in diameter embedded in an amorphous matrix which is rich in cobalt. From Mössbauer spectroscopy studies we have found that the crystalline α-FeCo phase in the nanocrystalline samples obtained by the conventional annealing is atomically ordered. Moreover, the order degree depends on the annealing time. As for the samples partially crystallized during rapid quenching, the crystalline α-FeCo phase is atomically disordered.

Published
2003

34. Catalytic Gas-Phase Glycerol Processing over SiO2-, Cu-, Ni- and Fe- Supported Au Nanoparticles.

Author

Kapkowski, Maciej, Siudyga, Tomasz, Sitko, Rafal, Lelątko, Józef, Szade, Jacek, Balin, Katarzyna, Klimontko, Joanna, Bartczak, Piotr, and Polanski, Jaroslaw

Subjects
GAS phase reactions, CATALYTIC activity, GLYCERIN, SILICA, GOLD nanoparticles, HYDROXYPROPANONE
Abstract

In this study, we investigated different metal pairings of Au nanoparticles (NPs) as potential catalysts for glycerol dehydration for the first time. All of the systems preferred the formation of hydroxyacetone (HYNE). Although the bimetallics that were tested, i.e., Au NPs supported on Ni, Fe and Cu appeared to be more active than the Au/SiO2 system, only Cu supported Au NPs gave high conversion (ca. 63%) and selectivity (ca. 70%) to HYNE. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

47. Influence of structural changes of Co78Si9B13 metallic glass on magnetic properties.

Author

JAKUBCZYK, EWA, LELĄTKO, JÓZEF, PAWLIK, KATARZYNA, and PRZYBYŁ, ANNA

Subjects
*METALLIC glasses, *COBALT, *SILICON, *BORON, *MAGNETIC properties, *CRYSTALLIZATION
Abstract

The primary crystallization of Co78Si9B13 metallic glass starts at 648 K and as a consequence of this the ε-Co(Si) phase with needle morphology is created. The second stage of crystallization (at 773 K) is the eutectic and as a result of this α-Co(Si) and boron phases: (Co,Si)3B, (Co,Si)2B are formed. The crystallites of these phases have layer morphology. These characteristic morphologies in the first and second stages lead to the increase in coercivity. [ABSTRACT FROM AUTHOR]

Published
2009

48. Study of Fe75Al25 Alloys by the Mössbauer Spectroscopy Positron Annihilation Lifetime Spectroscopy (PALS), XRD and SEM

Author

Hanc-Kuczkowska, Aneta, Kansy, Jerzy, Dercz, Grzegorz, Pająk, Lucjan, Lelątko, Józef, and Deniszczyk, Józef

Abstract

The structure, point defect and ordering parameter of Fe25Al samples is examined with the Mössbauer spectroscopy Positron Annihilation Lifetime Spectroscopy XRD and SEM. The studies are carried out for samples in as-cast state and after heat treatments: annealing for 24 hours at 900C (or 1050C) and either slow cooling with furnace or quenching to oil. Among the research method used, Mössbauer spectroscopy for determination of hyperfine structure parameters was adopted. These parameters, sensitive to changes in spin and charge electron densities in the nearest neighbourhood of a Mössbauer isotope nucleus, caused by specific configurations of atoms, are directly connected with the degree of ordering of a compound. Spectral analysis has been carried out using an authors’ software developed based on a theoretical model relating the shape of a Mössbauer spectrum to the sample microstructure. It has been shown that Mössbauer spectroscopy enables quantitative evaluation of the degree of ordering of phases occurring in samples characterised by large graining, in the case of which it is not possible to determine the long-range order parameter by X-ray diffraction. The PALS method only one type of defects is detected. The positron lifetime in these defects (V) suggests that they are quenched-in Fe-monovacancies (VFe). The vacancy concentration strongly depends on the rate of cooling.

Published
2013
Full Text
View/download PDF

49. Martensitic Transformation in Ti50Ni25Cu25 Shape Memory Alloy Studied by EBSD

Author

Goryczka, Tomasz and Lelątko, Józef

Abstract

Presented work summarizes studies done on the course of the martensitic transformation in the Ti50Ni25Cu25 alloy. Studies were carried out using scanning electron microscopy JEM 6480 equipped with an electron back scattered detector (EBSD) as well as a heating attachment. As-received ribbon was mainly amorphous. At the free side of the ribbon some fine randomly oriented crystalline grains were formed. During heating followed by cooling the reversible martensitic transformation occurred with sequence: B2↔B19. The crystallographic correlation between the B2 phase and the B19 martensite were confirmed. It allowed finding transformation matrix between both phases.

Published
2012
Full Text
View/download PDF

50. Structure of the Near Stoichiometric Thermally Treated Co2NiGa Heusler Compounds

Author

Prusik, Krystian, Morawiec, Henryk, Lelątko, Józef, Drdzeń, Andrzej, and Dercz, Grzegorz

Abstract

Series of the near stoichiometric two phase (martensite + , parent + ) Co2NiGa alloys were studied. Different thermal treatments changing the microstructure were applied. After annealing for 20 h at 9000C large  precipitates were dispersed, they decorated mainly the grain boundaries. For the alloys quenched from the 11000C modulated structures were observed. Furthermore, during aging at the 3500C ' precipitation process occured in the matrix.

Published
2010
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results