National Repository of Grey Literature 58 records found  beginprevious43 - 52next  jump to record: Search took 0.01 seconds. 
Influence of annealing conditions on Mossbauer spectroscopy parameters of Fe-Zn intermetallic phases
Zmrzlý, Martin ; Schneeweiss, Oldřich ; Houbaert, Y. ; Fiala, J.
The phase composition of galvannealed zinc coatings strongly depends on used annealing conditions. According to equilibrium binary phase diagram of iron and zinc, it is possible to find four intermetallic phases. They arise due to diffusion of zinc and have some certain limits of stability. After dipping into molten zinc the steel sheet proceeds to annealing furnace. Since this is the diffusion controlled and thermodynamically determined process, the composition of coating differs with temperature and time of annealing. Also within the phases themselves there are small but important differences of space arrangement of unit cells, what is clearly observable at Mossbauer spectra parameters ů isomer shifts, quadrupole splittings and relative areas of peaks.
Preparation of MgO-Ni3Fe nanocrystalline composite from spark eroded powder
Schneeweiss, Oldřich ; Jirásková, Yvonna ; Řepa, P.
Nanocomposites MgO-TM (TM = Ni3Fe, FeCo) were prepared by controlled heat treatment of compacted spark synthesised nanopowders. Main attention was paid to study of influence of interaction with surrounding atmosphere and adsorbed gases on phase composition and magnetic properties. Mössbauer spectroscopy, x-ray diffraction and TEM were used for phase analysis. Changes in structure and phase composition during annealing were detected using thermomagnetic curves and DTA/TG measure-ments and completed with gas analysis using mass spectroscopy.
Surface Structures of Stainless Steel Modified by Simultaneous Implantation of Nitrogen and Carbon
Jirásková, Yvonna ; Schneeweiss, Oldřich ; Blawert, C.
Surface modification of austenitic stainless steel using simultaneous implantation of carbon and nitrogen by PIII leads to significant improvement of surface hardness and wear resistance. The studies of the phase composition and microstructure is the aim of paper.
Comparison of site preferences of 57Co at grain boundaries in Fe-Si and Fe-Al alloys
Schneeweiss, Oldřich ; Jirásková, Yvonna ; Čermák, Jiří ; Lejček, P.
Emission Moessbauer spectroscopy was applied to the study of grain boundaries in the polycrystalline samples of iron rich Fe-Al and Fe-Si alloys. The results obtained on Fe-Al samples indicate complicated phase and chemical composition along grain boundaries (GBs). Neither homogeneous increase in Al concentration at GBs nor important site preference of Co atoms is observed. A large fraction of Co atoms occupy positions of lower symmetry. The results on Fe-Si show differencies in the chemical composition in grain interiors (GIs) and at GBs. An increase in Si concentration at GBs is observed there. In Fe-! & at.%Si sample a strong site preference of cobalt atoms at GBs is detected. The diffusing Co atoms prefer the lattice sites, which are expected to be occupied by structural vacancies in the D03 superstructure.

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1 Schneeweiss, O.
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