Papers by Author: G. Haneczok

Abstract: Magnetic properties of the Fe76.2Nb5.7B13.3Gd4.8, Fe69.6Nb5.2B12.2Gd13, Fe76.2Nb5.7B13.3Y4.8, Fe69.6Nb5.2B12.2Y13 bulk nanocrystalline alloys (mould casting technique) are presented and discussed. Measurements were carried out by the means of SQUID magnetometer (temperature range 2 K – 400 K, field up to 7 T) and magnetic balance (temperatures up to 1100 K). Microstructure was studied by the Mössbauer spectroscopy at room temperature. It was shown that the samples are nonocrystalline with α-Fe and different Fe-B, Y/Gd-Fe or Y/Gd-Fe-B compounds. The preparation method as well as the Gd addition causes a magnetic hardening of the studied alloys.

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: In the paper Fe82Nb2B16, Fe80Nb2B18 and Fe78Nb2B20 amorphous alloys, obtained by melt spinning, were examined. It was shown that the alloys studied in the as quenched state and in the relaxed amorphous state or in nanocrystalline state (after a suitable annealing) belong to very good soft magnetic materials with relatively high resistivity. The influence of annealing on brittleness as well as magnetic and electric properties measured at room temperature was examined. A correlation between sample microstructure (in the as quenched state and after annealing) and different physical properties is discussed. It was shown that the observed changes of relative magnetic permeability can be explained by changes of magnetoelastic energy, concentration of microvoids frozen during production process, effective anisotropy constant and magnetic polarisation.

Abstract: The aim of the present paper is to find correlations between structural changes and electrical, mechanical and magnetic properties in Fe78Si13B9, Fe76Nb2Si13B9, Fe75Cu1Nb2Si13B9, Fe75Cu1Zr1Co1Si13B9, amorphous and nanocrystalline alloys obtained by melt spinning technique. The influence of annealing on material brittleness, magnetic and electric properties was examined. It was found that the optimization of soft magnetic properties effect is a thermally activated process and its diffusion parameters were determined. It was shown that for the alloys containing Cu, Nb and Zr as alloying additions, the optimization process can be attributed to formation of a nanocrystalline phase. In contrast to this for the FeSiB and FeNbSiB alloys the optimization process should be related to the relaxed amorphous phase.

Abstract: The crystallization and optimization of magnetic properties effects in FeXSiB (X=Cu, V, Co, Zr, Nb) amorphous alloys were studied by applying X-ray diffraction methods, high resolution transmission electron microscopy (HRTEM), resistometric and magnetic measurements. The temperatures of the first and the second stage of crystallization, the 1h optimization annealing temperature and the Curie temperature were determined for different amorphous alloys. Activation energies of crystallization process were obtained by applying the Kissinger method. The influence of alloy additions on optimization effect and crystallization processes was carefully examined.