Nanocrystalline Ti Produced by Cryomilling and Consolidation by Severe Plastic Deformation

We report on a study of the nanocrystalline structure in Ti, which was produced by cryogenic milling followed by subsequent consolidation via severe plastic deformation using high pressure torsion. The mechanisms that are believed to be responsible for the formation of grains smaller than 40 nm are discussed and the influence of structural characteristics, such as nanometric grains and oxide nanoparticles, on Ti hardening is established

The influence of the microstructure morphology of two phase Ti-6Al-4V alloy on the mechanical properties of diffusion bonded joints

The influence of ultra fine grained (UFG) and coarse grained (CG) microstructure of the titanium alloy Ti-6Al-4V on the strength of a diffusion bonded (DB) joint was studied using a laboratory DB fixture and a new shear test rig. The DB process was carried out at 725°C and 825°C during 2 and 4 hours in a vacuum furnace. Coarsening of grain structure resulting from different DB cycles was quantified. The chain pores were observed at 725°C for both microstructure conditions bonded during 2 hours. The increase of bonding time up to 4 hours leads to subsequent elimination of the pores. The UFG samples bonded at 725°C showed a higher level of the shear strength than CG samples for both bonding times. The CG material demonstrated the highest shear strength after 4 hours of DB bonding at 825°C. The increase of the creep deformation of UFG samples when compared to the CG condition was observed as a result of DB at of 725° C during 4 hours

Decomposition process in a FeAuPd alloy nanostructured by severe plastic deformation

The decomposition process mechanisms have been investigated in a Fe50Au25Pd25 (at.%) alloy processed by severe plastic deformation. Phases were characterized by X-ray diffraction and microstructures were observed using transmission electron microscopy. In the coarse grain alloy homogenized and aged at $450 ^{circ}\mathrm{C}$, the bcc \alpha-Fe and fcc AuPd phases nucleate in the fcc supersaturated solid solution and grow by a discontinuous precipitation process resulting in a typical lamellar structure. The grain size of the homogenized FeAuPd alloy was reduced in a range of 50 to 100nm by high pressure torsion. Aging at $450 ^{circ}\mathrm{C}$ this nanostructure leads to the decomposition of the solid solution into an equi-axed microstructure. The grain growth is very limited during aging and the grain size remains under 100nm. The combination of two phases with different crystallographic structures (bcc \alpha-Fe and fcc AuPd) and of the nanoscaled grain size gives rise to a significant hardening of the allo

Method for complex web applications design

© Research India Publications. This article deals with peculiarities of design that are taken into consideration during practical development of complex information systems, made on the basis of web technologies, in particular during development of web applications. This article covers the majority of development aspects from the position of different methodologies of web applications design and lists design peculiarities differences in comparison with programme means that do not use web technologies. Web application architecture design according to block and modular principle is suggested. The main programme block will be responsible for users’ authorization, session provision, request of enclosed modules, connection to database and similar service functions. Administrative module will allow managing sets of modules, features of web applications, change informational content. It is also suggested that services of web application are designed according to modular principle as the ones that have their own managing modules and modules of data processing (working modules). Peculiarity of the suggested methodology is that the modules are made in the form of separate files that execute their own specific function and work strictly with their own tables in database. It is suggested to use traditional approach when creating a web application. It is connected with presence of a big number of different relational database control systems supported by web servers. Initially on the stage of database design datalogical models are being developed. They are oriented on data storage and processing environment. The difference of the suggested graphic interface is that navigation in the web application is managed by the user who may execute previously permitted actions on random following his way in navigating the interface. The method described in the article is used in web applications development for automated informational systems of diesel engines trials

Structural dynamic study of roof waterproofing materials

© 2014 by the author(s). The present research was aimed to develop the scientific applied principles and technologies of composite bituminous materials for civil engineering based on the investigation of the structures of polymer modifier and bitumen-polymer binder (BPB) on its basis with the use of nuclear magnetic resonance (NMR). The method of pulsed NMR was chosen as one of the rapid analysis methods that can be used for the analysis of bitumen-polymer systems, especially when assessing the group chemical composition of residual oil feedstock (ROF), bitumens and composite materials based on them. Using the method of pulsed NMR the regularities of the impact of modifier component composition on the changes of structural-group composition of the original and modified products were specified. Based on the results of research the optimal ratio of bitumen-polymer binder components was investigated, the manufacturability of the process for obtaining of composite bituminous materials for civil engineering with the aim of optimizing the quality of the final products was evaluated. Pulsed NMR - spectroscopy is suggested as input and output quality control of bituminous products. The regularities of redistribution of the phases with different molecular mobility and their relationship with the binder components were investigated. Rapid technique for quantifying the content of polymer in the solvent was developed

Developing reagents to reduce the flow resistance in the liquid stream

© Copyright 2016.It was established that the best efficiency for reduction of the hydraulic friction in condition of the closed circulating loop has reagent compositions D 157 (diproksamine) + CMC (carboxymethylcellulose), and MEA (monoethanolamine) + CMC. With increasing of water content up to 35 % the highest efficiency of the compositions of the reactants is observed due to the increase of the effect of Toms, according to the theory, the action of a composition can be managed in a needed way by choosing the right water-soluble and oil-soluble portions of reagents, affecting water and the hydrocarbon parts in the emulsion so that to achieve a certain Toms effect. With increasing of water content in oil emulsion up to 70 % and above, the addition of the reagent becomes ineffective. By experimental results we can expect a high economic effect in the practical use of the reagents, since the effectiveness of some of the reactants compared to the pumping oil emulsion without reactants reaches 35 %

Electron transport and optical properties of shallow GaAs/InGaAs/GaAs quantum wells with a thin central AlAs barrier

Shallow GaAs/InGaAs/GaAs quantum well structures with and without a three monolayer thick AlAs central barrier have been investigated for different well widths and Si doping levels. The transport parameters are determined by resistivity measurements in the temperature range 4-300 K and magnetotransport in magnetic fields up to 12 T. The (subband) carrier concentrations and mobilities are extracted from the Hall data and Shubnikov-de Haas oscillations. We find that the transport parameters are strongly affected by the insertion of the AlAs central barrier. Photoluminescence spectra, measured at 77 K, show an increase of the transition energies upon insertion of the barrier. The transport and optical data are analyzed with help of self-consistent calculations of the subband structure and envelope wave functions. Insertion of the AlAs central barrier changes the spatial distribution of the electron wave functions and leads to the formation of hybrid states, i.e. states which extend over the InGaAs and the delta-doped layer quantum wells.Comment: 14 pages, pdf fil

Effect of heat treatment on structural and phase transformations in the Ti49.5Ni50.5 alloy amorphized by high-pressure torsion

Results are presented for a study of the structural and phase transformations that occur in the titanium-nickelide shape-memory alloy Ti 49.5Ni50.5 subjected to heat treatment after deformation-induced amorphization by megaplastic high-pressure torsion (HPT) using five or ten revolutions of Bridgman anvils. The investigations were performed using transmission and scanning electron microscopy, X-ray diffraction, and measurements of the temperature dependences of electrical resistivity and magnetic susceptibility. It has been established that the crystallization of the alloy already occurs upon low-temperature treatment, beginning with ∼500 K. The evolution of the structure and the stage character of the development of crystallization and recrystallization processes depending on temperature have been determined. It has been shown that the annealing of the amorphized alloy makes it possible to obtain highly homogeneous nanostructured, submicrocrystalline, or bimodal states in the B2 austenite. A complete diagram of thermoelastic martensitic transformations of the B2 austenite has been constructed in the region from a nanostructured to a conventional polycrystalline state (with a grain size of 20-50 μm). The effect of size on the stabilization of austenite has been revealed and its specific features have been studied for the B2 → R and B2(R) → B19′ martensitic transformations depending on the structural state of the alloy. © 2013 Pleiades Publishing, Ltd

Modification of titanium and titanium dioxide surfaces by ion implantation: combined XPS and DFT study

The results of XPS measurements (core levels and valence bands) of P+, Ca+, P+Ca+ and Ca+P+ ion implanted (E=30 keV, D=1x1017 cm-2) commercially pure titanium (cp-Ti) and first-principles density functional theory (DFT) calculations demonstrates formation of various structural defects in titanium dioxide films formed on the surface of implanted materials. We have found that for double implantation (Ti:P+,Ca+ and Ti:Ca+,P+) the outermost surface layer formed mainly by Ca and P, respectively, i.e. the implantation sequence is very important. The DFT calculations show that under P+ and Ca+P+ ion implantation the formation energies for both cation (P-Ti) and anion (P-O) substitutions are comparable which can induce the creation of [PO4]3- and Ti-P species. For Ca+ and P+Ca+-ion implantation the calculated formation energies correspond to Ca2+-Ti4+ cation substitution. This conclusion is in agreement with XPS Ca 2p and Ti 2p core levels and valence band measurements and DFT calculations of electronic structure of related compounds. The conversion of implanted ions to Ca2+ and [PO4]3- species provides a good biocompatibility of cp-Ti for further formation of hydroxyapatite.Comment: 18 pages, 6 figures, 3 tables, accepted phys. stat. solidi (b

Peculiar properties of prophylactic medical care in organizations of various organizational and legal orientation

One of problem in prophylactic medical care – it is insufficiency of capability to provision assistance in phase of realization recommendation. It decreases of compliance and commitment of long term action.One of effective method of realization prophylactic medical care is a modern medical organization, such as fitness centers. We define characteristic of centers, which can be classify as medical organization. The article presents fitness centers as medical prophylactic organization. There are results of observation of 11246 patients. The proportion of people with risk factors among those who had first visited the fitness centers was 76,2%; cardiovascular risks – 32%; overweight and obesity – 43,4%, hypercholesterolemia – 32%; hyperglycemia – 11,2%. Behavioral factors (physical inactivity, smoking, irrational diet) was in 74,1%. In comparients organization of the possibility of implementation of recommendations on physical activity, education of patients, food rational nutrition balanced diet. The average number of visits per person is 49.2 per year. This confirms the fact that the studied fitness centers create favorable conditions for the primary and secondary prevention of non-communicable diseases.Недостаток мощностей медицинских организаций на этапе реализации профилактических рекомендаций существенно влияет на комплаенс и приверженность к долгосрочным профилактическим действиям. Одним из эффективных способов реализации профилактической помощи являются такие современные профилактические медицинские организации, как фитнес центр. Определены критерии фитнес центров, которые можно отнести к организациям, оказывающим профилактическую помощь. Приведены результаты обследования 11246 пациентов. Наличие факторов риска неинфекционных заболеваний среди занимающихся выявлено в 76,2%, кардиоваскулярных факторов риска - в 32,3%, повышенная масса тела и ожирение - в 43,4%, гиперхолистеринемия в 32%, гипергликемией в 11,2%. Поведенческие (гиподинамия, курение, нерациональное питание) встречались в 74.1%. Значимым отличием является организация возможности реализации рекомендаций по двигательной активности, образованию пациентов, пищевому режиму. Среднее количество посещений на одного человека 49,2 в год, что подтверждает наличие благоприятных условия для проведения первичной и вторичной профилактики неинфекционных заболеваний, а также возможность для фитнес центров быть высокоэффективным дополнением к уже существующим способам профилактической помощи, а также являться ее этапом в сочетании с другими медицинскими организациями