Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

The influence of warm swaging on the structure and properties of Ti-6Al-4V alloy was studied. Warm swaging of the alloy in the interval 680-500°C with the total strain of ε=2.66 was found to be resulted in the formation of a homogeneous globular microstructure with a grain size of 0.4μm in both longitudinal and transversal sections. Room temperature tensile strength and tensile elongation of the swaged alloy was 1315MPa and 10.5%, respectively. Ultrafine-grained Ti-6Al-4V alloy produced by swaging exhibited good workability at 600-700°

Twinning-induced formation of nanostructure in commercial-purity titanium

In the present work the influence of various parameters on formation of nano- or ultrafine-grained structure in commercial-purity titanium during large deformation was quantified using TEM and EBSD. The beneficial effect of twinning on the kinetics of microstructure refinement in titanium was revealed. It was shown that deformation twinning (and therefore nanostructure formation) can be intensified via decrease in temperature, increase in the initial grain size and decrease in the impurities content. The minimum grain size at which twinning can still operate in commercial-purity titanium was determined to be ~1μm. It was shown that rolling to a thickness strain of 93% at -196°C resulted in the formation of a microstructure with a grain/subgrain size ~80 n

Ionospheric effects during first 2 hours after the Chelyabinsk meteorite impact

This paper presents the analysis of ionospheric effects in the region close to the Chelyabinsk meteorite explosion at 03:20UT 2013 February 15 from the Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) EKB radar data, and from the Institute of Geophysics of Ural Branch of Russian Academy of Sciences (IG UB RAS) PARUS ionosonde data. Both instruments are located within the IG UB RAS Arti Observatory approximately 200 km northward from the estimated explosion site. According to the data obtained, the ionospheric disturbance caused by the meteorite flyby, explosion, and impact had high dynamics and amplitude. However, it obviously did not lead to a variation in the ionosphere mean parameters in the region above the disturbance center during the first 2 hours. Essential effects, however, were observed at more than 100-200 km from the explosion site and farther up to 1500 km.Comment: 30 pages, 15 figures, submitted to JAST

Kinetics of grain refinemet in metallic materials during large strain deformation

The development of ultrafine grained microstructures in austenitic stainless steel and pure titanium subjected to large strain deformation was comparatively studied. The change in the volume fractions of newly developed ultrafine grains was used to quantify the progress in grain refinement during plastic deformatio

Microstructure evolution of commercial-purity titanium during cryorolling

Electron backscatter diffraction and transmission electron microscopy have been used to analyze the microstructural evolution of titanium during rolling at a cryogenic temperature (T = –196°C). It has been found that intensive twinning at the cryogenic deformation temperature accelerates the kinetics of micro structure refinement. The quantitative analysis of microstructure evolution in titanium upon cryorolling has shown that structure evolution is mainly related to mechanical twinning in the initial stages cryorolling is discusse

Grain-structure development in heavily cold-rolled alpha-titanium

High-resolution electron back-scatter diffraction (EBSD) analysis was employed to establish mircostructure evolution in heavily cold-rolled alpha-titanium. After thickness reductions of 75% to 96%, significant microstructure and texture changes were documented. The surface area of high-angle grain boundaries was almost tripled, thus giving rise to an ultra-fine microstructure with a mean grain size of 0.6 μm. Moreover, orientation spread around typical ‘split-basal’ rolling texture substantially increased. These effects were suggested to be related to the enhancement of pyramidal 〈c+a〉 slip. Grain-structure development in heavily cold-rolled alpha-titanium (PDF Download Available

Multimodal optical diagnostics of the microhaemodynamics in upper and lower limbs

The introduction of optical non-invasive diagnostic methods into clinical practice can substantially advance in the detection of early microcirculatory disorders in patients with different diseases. This paper is devoted to the development and application of the optical non-invasive diagnostic approach for the detection and evaluation of the severity of microcirculatory and metabolic disorders in rheumatic diseases and diabetes mellitus. The proposed methods include the joint use of laser Doppler flowmetry, absorption spectroscopy and fluorescence spectroscopy in combination with functional tests. This technique showed the high diagnostic importance for the detection of disturbances in peripheral microhaemodynamics. These methods have been successfully tested as additional diagnostic techniques in the field of rheumatology and endocrinology. The sensitivity and specificity of the proposed diagnostic procedures have been evaluated.<br/

Microstructure and texture evolution of a high manganese TWIP steel during cryo-rolling

The influence of rolling at 77 K and 293 K to a true strain of 2.66 on the microstructure and texture evolution and mechanical behavior of a TWIP Fe-0.3C-23Mn-1.5Al steel was quantified. The microstructure evolution at both temperatures of deformation was associated with an increase in the dislocation density and extensive twinning, following by the development of a cell structure and shear band

Effect of second phase particles on mechanical properties and grain growth in a CoCrFeMnNi high entropy alloy

Effect of annealing of a cold-worked CoCrFeMnNi alloy at temperatures of 500-900°C for 1-50 h on the structure and mechanical properties was studied in the present wor