Solid State Phenomena Vols. 203-204

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.

Abstract: The aim of this work is to investigate structure and stress evolution in Au/Cu bilayer systems during deposition. The approach used here is based on an embedded atom method (EAM). interatomic potential database for different metal elements, their alloys and multilayers. We applied the kinematical scattering theory to calculate the X-ray scattering profiles. In this case the X-ray scattering techniques are used for the structural characterization of crystal structures obtained from simulation data. This method was applied to determine the lattice parameters in any directions. The lattice parameters in deposited layers were directly determined by the analysis of X-ray diffraction profiles. Results shows that on the interface of Au/Cu system, the crystalline lattice of Au layer is fitted to crystalline lattice of Cu layer. We found that deformation of the crystal lattice near the interface has a major influence on the stress.

Abstract: Abstract. Phase and structure analysis of CuCr2-xGdxSe4 (x=0.1÷0.3) synthesized using a solid state reaction method were carried out using X-Ray powder diffraction. All obtained compounds were found to be multi phase with the spinel phase being dominant up to x=0.1, indicating low solubility limit of gadolinium. Two compounds CuCr1.95Gd0.05Se4 and CuCr1.9Gd0.1Se4,. were chosen for a detailed structure refinement.

Abstract: In this paper phase composition of several steels was investigated by X-ray diffraction and conversion electron Mössbauer spectroscopy (CEMS) methods. Different heat treatments were performed on steel samples in order to obtain various phase compositions (containing bainitic ferrite, martensite and retained austenite). The diffraction patterns were analysed using the Rietveld method. Mössbauer spectra were fitted and studied for existent phases. A comparison between results obtained by each method was performed. Both methods revealed some supersaturation of carbon in the retained austenite and in the bainitic ferrite phases, various after different treatments. The quantitative phase composition measured by X-ray diffraction results differ significantly from the Mössbauer spectroscopy results. The possible reasons of the observed differences were discussed.

Abstract: During the process of leaching of roasted ore from fluidized-bed furnace a decrease of zinc (as ZnO) recovery was observed. Within the investigations a comprehensive structural analysis of samples from the process of roasting of zinc concentrates has been made. It has been found that one of the essential causes for zinc recovery decrease is a presence of (Zn,Fe)S sulphide in the ore, instead of pure zinc blende ZnS. Subsequently, (Zn,Fe)S iron blende is oxidized not to ZnO, but to a mixture where the main component is mixed (Zn,Fe)Fe₂O₄ oxide. Such oxide does not decompose into simple oxides during the process, which leads to a decrease of zinc recovery.

Abstract: Molecular dynamic simulations are used to study the structure and the evolution of stress during the deposition of atoms with different size on the (001) FCC plane. The relative size of deposited atoms is changed in the range from 0.75 to 1.0. To calculate the X-ray scattering profiles we applied the model that is based on the kinematical scattering theory. Deformation of the lattice parameters in deposited layers were directly determined by the analysis of X-ray diffraction profiles. It was found that the crystal lattice near the surface exhibits a major influence on the stress evolution. The deposited atoms form the same structure in entire systems, regardless of the their relative size.

Abstract: The titanium and titanium alloys endoprostheses surface may be improved by forming TiOx single layer or TiOx – hydroxyapatite multi – layer on their surface. Biocompatibility of TiOx layers depends highly on their microstructure, parameters of formation method and properties of substrate. Paper presents microstructure of the TiOx layer formed on titanium surface in fluidized bed reactor. In order to evaluate thickness, microstructure and Ti:O concentration ratio X-ray diffraction, Confocal Raman microspectroscopy methods are realized. Methods enables to define every type of TiOx structure simultaneously including rutile which dominates in investigated layers.

Abstract: The paper attempts to determine the changes in the γ’ lattice orientation of aircraft engine turbine blades made of the CMSX-4 single crystal nickel superalloy. The solidification of a hollow assembly structure for 2 various blades was carried out by the Bridgman method at the Research and Development Laboratory for Aerospace Materials at Rzeszow University of Technology using an ALD Vacuum Technologies vacuum furnace. Ceramic moulds made of Al2O3 were used. The alloy temperature during casting into the mould amounted to 1550°C. The specimens for Laue method tests were cut out from the blades at withdrawal rates of 3 and 4 mm/min.

Abstract: Nickel-based single-crystal superalloys are widely used for production of high pressure turbine blades. The studied blades were obtained in an ALD Vacuum Technologies furnace by the Bridgman technique. Crystallization process was carried out with drawing rates of 3 mm/min and 5 mm/min. The dendrite microstructure based on the γ/γ’ phases and their defects was characterized using X-Ray topography, Laue diffraction, transmission electron microscopy. The defect structure samples were examined with the positron annihilation lifetime spectroscopy. It was found that crystal orientation, lattice parameter of γ’ phase and concentration of defects are correlated. The defect concentration increases in some areas which was the result of deviation of the primary dendrite arm from crystallization direction . Only one type of point defects was detected.

Abstract: The article presents the comparison of two methods: classical X-ray topography and the modern automatic X-ray OD-EFG diffractometer. Both methods were applied to study the crystal orientation of turbine blades of single crystal nickel-based superalloys. The solidification of a hollow assembly structure for 5 various blades was carried out by the Bridgman method at the Research and Development Laboratory for Aerospace Materials at Rzeszow University of Technology using an ALD Vacuum Technologies vacuum furnace. Ceramic moulds made of Al2O3 were used. The alloy temperature during casting into the mould amounted to 1550°C. The specimens for Laue method tests were cut out from the blades at withdrawal rates of 1, 2, 3, 4, and 5 mm/min.