Formation of dendrite domain structures in stoichiometric lithium niobate at elevated temperatures

Formation of the dendrite-type self-organized domain structures during polarization reversal at elevated temperatures (above 230°C) has been revealed and studied in stoichiometric lithium niobate LiNbO3 single crystals. Optical, confocal Raman, scanning electron, and piezoelectric force microscopy have been used for domain visualization. It has been shown experimentally that formation of the dendrite-like structures has been attributed to correlated nucleation caused by a field distribution in the vicinity of the charged domain walls. © 2012 American Institute of Physics

Examining the structure of mill rolls made of 9X2MΦ and 8X3CΓΦ steels using the ultrasonic method for quality control

The microstructure of specimens of 9X2MΦ and 8X3CΓΦ steels taken from working rolls of a reversing mill was examined. A correlation between characteristics of the crystal structure of the metal and the intensified attenuation of ultrasonic waves was found. Ultrasonic inspection was carried out using an ultrasonic flaw detector (Krautkramer Co.). The microstructure was examined by means of traditional metallographic analysis methods, which were implemented using a scanning electron microscope; X-ray spectral microanalysis and electron backscatter diffraction were used. The morphology and elemental composition of discontinuity flaws were studied; as well, phase maps, crystallite misorientation histograms, and Taylor factor maps were plotted for specimens taken from the defect zone of a 9X2MΦ steel working roll. © 2013 Pleiades Publishing, Ltd

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СТРУКТУРНОГО СОСТОЯНИЯ РАСПЛАВА НА КРИСТАЛЛИЧЕСКОЕ СТРОЕНИЕ И МЕХАНИЧЕСКИЕ СВОЙСТВА ФАЗ СПЛАВА AL-50 МАС.%SN МЕТОДОМ НАНОИНДЕНТИРОВАНИЯ

Nanoindentation is used to measure Young's modulus, the hardness, the plasticity, and the yield strength of the phases in Al-50 wt % Sn alloy samples prepared by a traditional method and using liquid-state homogenization. The effect of an increase in the cooling rate by an order of magnitude and alloying with 0.06 wt % Ti or 1 wt % Zr on the mechanical properties of the phases in the Al-50 wt % Sn alloy is studied. The most substantial effect on Young's modulus of the phases in the Al-50 wt % Sn alloy is found to be exerted by the homogenization of the metallic liquid and the introduction of zirconium in the alloy melt: the metal forming of an ingot is improved substantially. © 2013 Pleiades Publishing, Ltd

Study of structure-property relationship in polycrystalline steels based on analysis of EBSD data

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used

SEM-investigating microstructure of cast AlNiCuFeCo high entropy alloys formations a liquid-phase separation

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used

Domain formation by ion beam in lithium niobate crystal with suppression of surface charging by electron and UV-flood guns

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used. The research was made possible by the Russian Science Foundation (grant № 17-72-10152)

SEM investigation of the microstructure of cast CuNiAlCoFe equiatomic high entropy alloy

Microheterogeneity and crystallization conditions of the equiatomic high-entropy CuNiAlCoFe alloy were studied by measuring the viscosity during heating/cooling, as well as visualizing the microstructure after solidification. The CuNiAlCoFe liquid alloy showed different temperature dependences of viscosity upon heating to 2070 K and subsequent cooling. Since the coinciding part of the temperature dependences was absent, complete destruction of the microheterogeneity of the melt after heating to 2070 K did not occur. Heating the melt to higher temperatures was not possible due to the evaporation of the metal. The melt viscosity during cooling is higher than that during heating; this is observed when microheterogeneity is dispersed. The CuNiAlCoFe alloy obtained as a result of the experiment at a crystallization rate of 10 K/s had a typical microstructure of cast dendrite. Dendrites consisted of a eutectic (α-Al+CuAl2+Cu4NiAl7) and included primary crystals of CoCu2Al7 and FeCu2Al7. The interdendritic space contained small Cu4NiAl7 crystals. © Published under licence by IOP Publishing Ltd

FERROELECTRIC DOMAIN PATTERNING BY FOCUSED ION BEAM IRRADIATION OF [100]-CUT [001]-POLED PMN-PT SINGLE CRYSTALS

The formation of domain structure via charge injection controlled by focused ion beam irradiation by means of a lithographic system in PMN-PT single crystals with a surface arti-ficial dielectric layer has been studied experimentally. The results explained in terms of the kinetic approach.The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Fed-eral University was used. The research was made possible by the Russian Science Foundation (grant № 19-72-00091)

Shape of isolated domains in lithium tantalate single crystals at elevated temperatures

The shape of isolated domains has been investigated in congruent lithium tantalate (CLT) single crystals at elevated temperatures and analyzed in terms of kinetic approach. The obtained temperature dependence of the growing domain shape in CLT including circular shape at temperatures above 190 °C has been attributed to increase of relative input of isotropic ionic conductivity. The observed nonstop wall motion and independent domain growth after merging in CLT as opposed to stoichiometric lithium tantalate have been attributed to difference in wall orientation. The computer simulation has confirmed applicability of the kinetic approach to the domain shape explanation. © 2013 AIP Publishing LLC