Papers by Author: Małgorzata Karolus

Abstract: Amorphous alloys based on iron, obtained by melt spinning technique, are modern and very promising soft magnetic materials. The thermal annealing at temperatures closed to the crystallization temperature can cause an increase of magnetic permeability more than 10 times i.e. the so called enhancement of soft magnetic properties effect (ESMP). It is usually explained by formation of iron nanocrystallites in amorphous surroundings or by formation of the relaxed amorphous phase. Such a microstructure leads to averaging out of magnetic anisotropy and cause the ESMP.

Abstract: In this paper there are presented results of structure analyses of the Fe78Nb2B20 amorphous alloy after annealing. Basing on the initial analyses the “hypothetical” model structure was chosen as the combination of different kind of the Fe structure deformations: change of unit cell parameters (change of unit cell shape) and change of line broadening (change of crystallite size). The crystallite size (in meaning of the size of the ordered regions) for the amorphous state is in a range of 7 – 37 Å and for the crystalline state is about of 1100 Å. The comparison of the values of the unit cell parameters shows that the value of the basic – hypothetical unit cell in an amorphous state is bigger of 0.2 Å than in a crystalline state. After crystallisation there are detected Fe and Fe3B phases.

Abstract: In this paper we present self-designed mould suction casting apparatus allowing preparation of bulk samples in a form of rods (1.5 mm in diameter and about 3 cm in length). Making use of the apparatus the following compositions of Fe80Nb6B14, Fe76.2Nb5.7B13.8Gd4.8, Fe69.9Nb5.2B12.2Gd13, Fe76.2Nb5.7B13.8Y4.8, Fe69.9Nb5.2B12.2Y13, Fe61.5Nb4.6B10.8Y23.1 alloys were prepared. Phase and microstructure identification were curried out by making use of X-ray diffraction measurements. The obtained results show that the constructed apparatus fulfill all conditions required for such technique. Gadolinium as an alloying addition causes full amorphization in the case of the Fe76.2Nb5.7B13.8Gd4.8 alloy. In the other cases the structure was found to be nanocrystalline which is discussed in the paper.

Abstract: The Zinc composite coatings containing Ni powder were obtained by the electrodeposition and electroless methods. Electrodeposited Zn+Ni coatings were plated with the current density jk = 150 mA/cm2 from the zinc chloride bath containing the suspension of nickel powder. Electroless (Zn-Ni)+Ni coatings were obtained by chemical reduction of Ni2+ and Zn2+ ions from the sulphate bath containing sodium hypophosphite as a reducing agent and mechanically dispersed Ni powder suspension. The thickness of (Zn-Ni)+Ni layer was ~8 m. In order to enhance the Zn content the obtained coatings were covered with the electrolytic Zn layers of different thickness (5 m, 8 m and 14 m) – (Zn-Ni)+Ni/Zn. The thermal treatment of the obtained composites was carried out at a temperature of 320oC, during 2h in argon atmosphere. The electrodeposited coatings show the presence of Zn, Ni(Zn) and ZnO phases. The electroless coatings show the presence of Zn, Ni(Zn) and ZnO phases. The additional electrodeposition of Zn leads to the creation of dilayer coatings (Zn-Ni)+Ni/Zn. The annealing of such obtained coatings leads to the creation of Ni2Zn11 intermetalic phase. The average Ni(Zn) and Ni crystallite size before annealing is in a range of 200 Å and after annealing the size is increasing to values of 600-800 Å.

Abstract: The X-ray reflectivity measurements were used for the analyses of the SiC and SiN thin layers. Density, roughness and the thickness were determined for searching materials. The calculations and simulations were carried out using the WinGixa software. The obtained results show that the studied layers are non-homogenous and there are consist of “sub-layers” rich in Si-C, Si-N, SI-O phases. Moreover, the presence of the main amorphous phase was observed in all searching samples.

Abstract: In structure studies performed using the Grazing Incident X-ray Diffraction Geometry (GIXD) for different incident angles it was indicated that the Si-N layers are non-homogenous and their structure depends on the penetration depth. The layers close to substrate (α = 2, 1°) show the presence of the Si3N4, SiO2, SiO2, SiC phases and an amorphous Si-N phase as well. The layers near the surface (α = 0.5; 0.25; 0.15°) are poorer in Si-N phases. There are only observed the presence of the Si3N4 and SiO2 phases. The obtained results confirm the non-homogenity of layers.

Abstract: Electronic structures of electrodeposited Ni-Mo layers with polyethylene, polytiophene and polypyrrole were studied by Auger electron spectroscopy using the Cini-Sawatzky's model. Comparison of the theoretical and experimental lines was carried out using the asymmetry parameter of the spectral lines. It is pointed out that the changes of the spectral main lines Ni and Mo are connected with the ways of polymerization. It has been also shown that the application of the Cini-Sawaztky model to the experimental spectral lines can be used to explain the distortion appearing in the materials. Model parameters, i.e., intra-atomic correlation and bandwidth were determined.

Abstract: Electrolytical layers of Ni-Mo alloys with polypyrrole, polytiofene and polyethylene were deposited on steel substrate (St3S, 4 cm2). After structural analyses of as quenched samples performed by X-ray diffraction it was noticed that the solid solution of Mo in Ni is observed. After annealing in an argon atmosphere the solid solution of Mo in Ni is becomeing more stable and crystalites are growing to the size of 200 – 300 Å. After annealing in an air atmosphere X-ray diffraction patterns show presence of phases: NiO, MoO, NiCO3, Mo2N. The unit cell parameters of solid solution after annealing are smaller than parameters of as quenched samples what means that the solid solution has been decomposing.