Microstructure evolution in a Cu-Cr-Zr alloy during warm intense plastic straining

The effect of equal channel angular pressing at a temperature of 200°C to a total strain of 12 on microstructure evolution and mechanical properties of a Cu-0.87wt.%Cr- 0.06wt.%Zr was investigated. New ultrafine grains resulted from gradual increase in the misorientations of strain-induced low-angle boundaries with increasing number of passes. Therefore, the development of ultrafine grains is considered as a kind of dynamic recrystallization. The equal channel angular pressing to a total strain of 12 resulted in the formation of almost equiaxed ultrafine grained structure with an average grain size of 0.5 Tm and 0.7 Tm in the solution treated and aged samples, respectively. At the same time, the fraction of ultrafine grains comprises 0.77 in the solution treated samples and 0.72 in the aged samples. Significant grain refinement led to the remarkable increase of the ultimate tensile strength up to 550 MP

Stabilising the Blue Phases

We present an investigation of the phase diagram of cholesteric liquid crystals within the framework of Landau - de Gennes theory. The free energy is modified to incorporate all three Frank elastic constants and to allow for a temperature dependent pitch in the cholesteric phase. It is found that the region of stability of the cubic blue phases depends significantly on the value of the elastic constants, being reduced when the bend elastic constant is larger than splay and when twist is smaller than the other two. Most dramatically we find a large increase in the region of stability of blue phase I, and a qualitative change in the phase diagram, in a system where the cholesteric phase displays helix inversion.Comment: 15 pages, 6 figure

Microstructure and crystallographic texture of silicon iron modified by torsion under quasihydrostatic pressure

The electron backscatter diffraction, X-ray diffraction analysis, electromotive force instantaneous measurement, microhardness and coercive force measurement techniques are used to explore the development of the microstructure, crystallographic texture and physico-mechanical properties of silicon iron (Fe-3% Si) alloy under quasi-hydrostatic pressure in a Bridgman anvil. It is found that the alloy deformation is accompanied by its significant hardenin

Effect of deformation temperature on formation of ultrafine-grained structure in the age-hardenable Cu-Cr-Zr alloy

The effect of the temperature of plastic deformation performed by equal channel angular pressing on the structure and physical and mechanical properties of the age-hardenable Cu-Cr-Zr alloy has been studied. Plastic deformation results in the formation of an ultrafine-grained structure in some regions with an average grain size smaller than 1 μm, a supersaturated solid solution decomposition, and the precipitation of disperse particle

Structure and texture evolution of the metastable austenitic steel during cold working

This work studies the structure and texture evolution in the 03Kh19N10 corrosion-resistant metastable metastable austenitic steel (0.05C-18.2Cr-8.8Ni-1.65Mn-0.43Si-0.05P-0.04S wt %, and Fe for balance) during cold rolling, which results in twinning and martensitic transformation. The strain-induced martensite nucleates heterogeneously in the microshear bands and at their intersection

System for Synchronous Detection Trace of Explosives and Drags Substances on Human Fingers

AbstractThe sampling unit of the device, based on ion mobility spectroscopy technique, for detection of ultra small (trace) substances concentration on human fingers and documents is described. The vapor pressure of many dangerous substances is very small; so the heating of an investigated surface is needed for effective detection. However the direct heating of the human fingers by irradiation of the gas-discharge lamp is not effective because a small concentration of the melamine (pigment of the black or brown color) in the skin of the human palm. Therefore in this work the combination of the two methods is used: a grid is heated by the irradiation of the gas-discharge lamp and a grid heats the surface of the finger which is pressed to a grid

Water uptake and transport properties of La1-xCaxScO3-α proton-conducting oxides

In this study, oxide materials La1-xCaxScO3-α (x = 0.03, 0.05 and 0.10) were synthesized by the citric-nitrate combustion method. Single-phase solid solutions were obtained in the case of calcium content x=0.03 and 0.05,whereas a calcium-enriched impurity phasewas found at x=0.10. Water uptake and release were studied by means of thermogravimetric analysis, thermodesorption spectroscopy and dilatometry. It was shown that lower calcium content in the main phase leads to a decrease in the water uptake. Conductivity wasmeasured by four-probe direct current (DC) and two-probe ascension current (AC)methods at different temperatures, pO2 and pH2O. The effects of phase composition,microstructure and defect structure on electrical conductivity, as well as correlation between conductivity and water uptake experiments, were discussed. The contribution of ionic conductivity of La1-xCaxScO3-α rises with decreasing temperature and increasing humidity. The domination of proton conductivity at temperatures below 500 °C under oxidizing and reducing atmospheres is exhibited. Water uptake and release as well as transport properties of La1-xCaxScO3-α are compared with the properties of similar proton electrolytes, La1-xSrxScO3-α, and the possible reasons for their differences were discussed. © 2019 by the authors.Russian Science Foundation, RSF: 16-13-00053Government Council on Grants, Russian FederationMinistry of Education and Science of the Republic of KazakhstanFunding: The research was partially supported by the Russian Science Foundation (Grant №16-13-00053) and the Ministry of Education and Science of the Republic of Kazakhstan (Project No. AP05130148). The education activity of Ph.D. and students involved into this work is supported by Act 211 of Government of the Russian Federation, agreement No. 02.A03.21.0006

Deformation Aging OF Cu–Cr–Zr Alloys during Equal Channel Angular Pressing

A method of estimation of volume fraction of dispersed particles precipitated during equal channel angular pressing in Cu–Cr–Zr alloys was elaborated. The method involves the Matthiessen relationship for determination of electron scattering on solutes. The particles volume fraction calculated by the proposed approach correlated well (R 2 = 0,92) with the particles volume fraction measured by transmission electron microscopy.Предложен способ определения объемной доли дисперсных частиц, выделяющихся в процессе равноканального углового прессования (РКУП) Cu–Cr–Zr сплавов. Метод основан на применение зависимости Маттисона для оценки рассеяния электронов на атомах замещения. Результаты расчета объемной доли частиц с помощью предложенного подхода хорошо коррелируют (R 2 = 0,92) с объемной долей частиц, измеренной методом просвечивающей электронной микроскопии (ПЭМ)

GRAIN REFINEMENT AND STRENGTHENING OF A Cu–0.1Cr–0.6Zr ALLOY SUBJECTED TO EQUAL CHANNEL ANGULAR PRESSING

Исследована эволюция микроструктуры и механические свойства сплава Cu–0,1 % Cr–0,06 % Zr после равноканального углового прессования (РКУП) при температуре 400 °С. Установлено, что РКУП приводит к уменьшению среднего размера зерен до субмикрокристаллического состояния после 12 проходов. Оценка вкладов зернограничного, дислокационного и дисперсионного упрочнения в общее упрочнение проводилась с использованием модифицированного соотношения Холла-Петча. Основной вклад вносит дислокационное упрочнение, которое резко возрастает после 1 прохода РКУП до 200 МПа и почти не меняется с увеличением степени деформации.The microstructure evolution and mechanical properties of a Cu–0.1Cr–0.06Zr alloy subjected to equal channel angular pressing (ECAP) at temperature 400 °C were examined. The ECAP processing resulted in gradual decrease of grain size below 1 μm after 12 ECAP passes. The main contribution to the strengthening during ECAP processing was provided by the dislocation density, which increased to 200 MPa after the first ECAP pass and did not va ry remarkably with further straining.Работа выполнена при финансовой поддержке Министерства образования и науки РФ (грант № 14.Y31.16.8446-НШ)