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Mossbauer study of amorphous and nanocrystalline FeZrB(Cu) alloys

100%

Kopcewicz M. , Grabias A.

tom Vol. 31, No. 1

96-96

The possibility of producing nanocrystalline very soft magnetic materials by utilizing the first step of crystallization of amorphous alloys is widely recognized. A new class of iron based amorphous FeZrB alloys is of particular interest because of their superior magnetic properties (higher saturation magnetization and permeability) as compared to more conventional FeCuNbSiB alloys. The nanocrystalline phase formed due to annealing of amorphous FeZrB and FeZrBCu alloys is bcc-Fe. The excellence of soft magnetic properties is understood in terms of the reduction of magnetic anisotropy due to formation of nanoscale bcc-Fe grains. [...]

The influence of Ge on antiferromagnetic coupling in Fe/Si multilayers

80%

Wandziuk P. , Luciński T. , Kopcewicz M.

Materials Science Poland

2006

tom Vol. 24, No. 3

861--865

The magnetic and structural properties of sputtered Fe/Ge, Fe/Ge/Si/Ge and Fe/Si/Ge/Si multilayers were studied. Magnetization measurements revealed the absence of antiferromagnetic coupling for Ge spacer. It was found that during the multilayer deposition a 0.5 nm thick Fe layer at each Fe/Ge interface became nonferromagnetic leading to formation of antiferromagnetic structures. Mössbauer spectra showed the existance of ferro- and/or antiferromagnetic structures at Fe/Ge interfaces, and ferromagnetic and paramagnetic structures at Fe/Si interfaces. We have found that substitution of Si by at least 0.5 nm of Ge in the 1.1 nm thick Si spacer led to disappearance of antiferromagnetic coupling in the Fe/Si multilayers.

Animal models of skin regeneration

80%

Gawronska-Kozak B. , Grabowska A. , Kopcewicz M.

nr 1

Interaction of nitrogen atoms in expanded austenite formed in pure iron by intense nitrogen plasma pulses

51%

Piekoszewski J. , Sartowska B. , Waliś L. , Werner Z. , Kopcewicz M. , Prokert F. , Stanisławski J. , Kalinowska J. , Szymczyk W.

tom Vol. 49, nr 2

57-60

The paper presents the results of experiments on modification of pure iron by high-intensity nitrogen pulsed-plasma treatment. The duration of nitrogen plasma pulses is approximately 1 mi s, and the energy density amounts to about 5 J/cm2. Such pulses are capable to melt the surface layer of the substrate (1- 2 mi m) and to introduce a significant concentration of nitrogen into the molten layer. Nuclear reaction analysis (NRA), X-ray diffraction (XRD) and conversion electron Mössbauer spectroscopy (CEMS) were used for characterisation of the treated samples. The main results of the data analysis are as follows: it has been stated that such treatment leads to gradual transformation of initial alfa-phase into austenitic gamma structure in which expanded austenite gammaN is present. Treatment with 20 pulses results in almost complete transformation and introduces a retained dose of nitrogen estimated as 5.5 × 1017 N/cm2. The susceptibility for expansion of the lattice transformed to austenite in this way is smaller than in the case when the steel subjected to conventional nitriding is originally of austenite type. The analysis of the ratio of alfa to gammaN as a function of the nitrogen content provides a firm evidence that strong repulsion forces act between the first and the second nearest-neighbour nitrogen atoms in the fcc austenitic structure formed as a result of nitriding of pure iron by intense nitrogen plasma pulses.