Solid State Phenomena Vol. 163

Abstract: The high quality Sr0.61Ba0.39Nb2O6 (SBN61) single crystals without any striations were obtained by Czochralski pulling method. The temperature dependence of the lattice parameters of the investigated crystals was studied using a precision X-ray Bond's method. The angular precision of the goniometer 1 arcsine and metric value of Cu K1 (λ = 1.54059292Å) allowed to obtain high precision and accuracy of lattice parameter measurements. The received results allowed to determine the Curie temperature and character of the phase transition in this material. The lattice parameter a monotonically increases and shows hardly visible inflection point at TC when increasing the temperature. The temperature dependence of the lattice parameter c displays quite distinct temperature behaviour. Contrastingly, it decreases with increasing the temperature experiencing an evident anomaly in the vicinity of the structural phase transition point. Obtained value of the ferroelectric phase transition point is TC = 346 ± 3K.

Abstract: The subject of the study was an examination of the lattice parameter variations of the constituent phases in CoSi2-Si eutectic composite according to the vertical axes of samples. A preparation of samples has been conducted using Bridgman and Czochralski techniques. The aim of the study was to establish an influence of applied preparation method on a stability of appropriate lattice parameters. It was shown that the constituent phases of the CoSi2-Si eutectic samples obtained via Czochralski technique are distinguished by a higher stability of the lattice parameter than samples obtained using Bridgman technique.

Abstract: The Al-Pd-Cr alloy system was investigated at 680 to 990°C in the compositional range above 60 at.% Al. The binary Al-Cr , μ and phases dissolves up to 1 at.% of Al, the η-phase extends up to 2 at.% of Pd and the 2-phase extends up to 3 at.% of Pd, respectively. The binary Al-Pd -phases dissolves up to 3 at.% of Cr and -phase up to 4 at.% Cr. Close to the high-Pd limit of the -range a ternary phase is formed between about Al78Pd4Cr18, Al77Pd10Cr13 and Al74Pd7Cr19. Its structure is orthorhombic with lattice parameters: a = 1.47, b = 1.24 and c = 1.25 nm, resembling the lattice parameters of the high-temperature Al3Mn phase. A hexagonal structure with a = 1.77 and c = 1.25 nm resembling Al-Ni(Cu)-Cr ζ-phase [1-3] was revealed around Al81.5Pd1.5Cr27 and another hexagonal structure with very close lattice parameters around Al73Pd11Cr16. Another ternary phase was found in 970°C around the Al77.5Pd1.5Cr21 composition. It has orthorhombic structure with a = 1.24, b = 3.46 and c = 2.04 nm resembling the ternary -phase in Al-Ni-Cr. An additional orthorhombic phase with a = 2.48, b= 3.87 and c = 2.04 nm was found to be formed between about Al82Pd4Cr14, Al79Pd4Cr17 and Al79Pd9Cr12.

Abstract: Crystal-quasicrystal columnar composites (CQ composites) of Al Cu Fe alloy subject to tensile strain at room temperature were studied by the reflective X ray topography. In those composites singlecrystalline β phase occurred as the matrix and rods consisting of quasicrystalline ψ phase and crystalline λ phase as the reinforcement. X-ray topograms of plate like composite specimens were obtained using reflexes of singlecrystalline matrix. It has been found that at strains ε up to 0.33% in a linear range of stress strain σ(ε) relationship the topograms remain unchanged. Instead, at ε higher than 0.33% significant contract changes have been observed in some areas of topograms. It has been determined that at ε higher than 0.33% the components of misorientation angle of those areas increase with increasing strain. Methods of powder phase analysis, metallographic examinations by means of optical microscopy methods and X-ray diffraction topography methods were used.

Abstract: The columnar composites obtained “in situ” through solidification of Al61Cu27Fe12 alloy by the Bridgman method were studied. It has been verified that the matrix consisted of cubic single crystal β phase and the reinforcement of icosahedral quasicrystal ψ phase and monoclinic crystal λ phase, which have the form of rods. This kind of composites will be named the Al-Cu-Fe crystal-quasicrystal (CQ) composites. The effect of heating from a temperature of about 100°C to about 650°C on the stress-strain relationships σ(ε) of parallel samples was studied. Additionally, the σ(ε) relationship was defined in cyclic load-unload tests at different temperatures. The composites were examined by powder X-ray diffraction and scanning electron microscope.

Abstract: The paper presents the investigation of the expansibility of an Al-Si alloy in the form of a protective coating applied on a steel substrate and as a conventional cast, respectively. Examinations were carried out in the temperature range of troom÷220°C using the diffractometric technique based on reflections (311), (222), (400), and (331) from the Al solid solution. It was demonstrated that the coating exhibited better thermal expansibility compared to the cast, and its thermal expansion coefficient was close to the standard values for alloys of the same chemical composition. For the cast, the thermal expansion coefficient was lower by approx. 25% in relation to the standard value. It was also found that the soaking of alloys during X-ray examination reduced their texturing and caused changes in the microstructure of both the coating and the cast by thinning the silicon crystals and rounding their edges.

Abstract: This paper presents the results of X-ray research on the structure of Cu/Ni multilayers magnetron-deposited on a Si (100) substrate. The multilayers, each consisting of a hundred Cu/Ni double-layers, but with a variable thickness of the Ni (1,2÷3nm) sublayer, were investigated. The thickness of the Cu sublayer was the same for all multilayers investigated and equalled 2nm. X-ray measurements were taken using filtered radiation with λCu=0.15405 nm and λCo=0.17902nm. The coatings were examined in respect of the angle at which the (111) reflection and satellite peaks appeared together. The obtained reflections were fitted using the Pseudo Voight curves. The thickness of the multilayer periods, resulting from the analysis of the diffraction pattern obtained for the above wavelengths of radiation, was compared. The thicknesses closest to those assumed in the deposition process were obtained for multilayers examined using radiation with Cu and utilizing the position of both satellite peaks, and multilayers examined using radiation with Co and utilizing the position of the main Cu/Ni(111) reflection and the S-1 satellite reflection.

Abstract: Kinetics of deformation induced martensitic transformation in metastable austenitic AISI 301 steel was characterized by several techniques including classical light metallography, X-ray diffraction, neutron diffraction and electron back scattered diffraction. In order to characterize the martensitic transformation, several specimens were tensile pre-deformed to 5%, 10% and 20% of plastic deformation and compared with non-deformed state. During straining, the volume fraction of α’-martensite rapidly prevails over the volume fraction of original austenite and reach the value circa 70%.

Abstract: In this work, we employed the Mössbauer spectroscopy in a study of point defect formation in intermetallic phases of the B2 structure from the Fe-Al system as a function of Al concentration. We present the values of the 57Fe isomer shift and quadruple splitting for the components describing the point defect in the local environment of a Mössbauer nuclide. The concentration of the Fe vacancies and Fe atoms substituting Al (Fe-AS) are determined. The results shown that an increase in Al content causes an increase in vacancy and Fe-AS