An alloy design approach for titanium alloys is presented. New alloys are isolated, manufactured and tested with an emphasis on the superplastic response. The superplastic effect is found to be ...optimal between 650 to 750∘C at strain rates between 8.3×10−2 and 8.3×10−3/s – this is a substantial improvement in terms of temperature and deformation rates over traditional titanium alloys such as Ti–6Al–4V. Elongations approaching ∼2000% are demonstrated. Electron backscatter diffraction studies confirm a randomisation of texture and absence of significant intragranular dislocation density, confirming superplasticity and thus grain-boundary sliding as the overarching deformation mechanism. At strain rates faster than 0.01/s, the alloys exhibit large elongations (∼200–500%) but softening is evident and lower ductility results. Our results reveal that the physical factors controlling the alloy composition/property/manufacturing interrelationship are understood and quantified. Physically-based constitutive equations are presented and used to demonstrate the practical advantages of the designed alloys.
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The “abc” deformation method for production of large-scale billets with submicrocrystalline structure was developed. A large billet of Ti–6Al–4V alloy (150-mm diameter
×
200-mm length) with a ...homogeneous submicrocrystalline structure was produced. The refined structure with a grain/subgrain size of about 0.4
μm leads to a substantial mechanical properties improvement.
Human development research implies the use of complex interdisciplinary approach. Human development measuring and assessment should not be restricted to calculating and analyzing integral index and ...its components. Human development is first of all a social process mainly carried out by individuals and their activity (work, education, socio-cultural activities etc.). They ought to be supplemented and verified by sociological analysis of subjective estimates, ideas and views of population about quality and standards of its living, health, education and other values. The article discusses human development assessment in the Republic of Bashkortostan, which along with macroeconomic indicators of regional development embraces feelings, interests and needs of people as well as opportunities to realize their human potential.
This paper reports on investigations of the solid state formability and weldability of Ti-6Al-4V titanium alloy sheet with submicrocrystalline structure (grain size 0·5 and 0·8 μm) under superplastic ...conditions at temperatures of 700 and 800°C. It has been established that the submicrocrystalline condition of the sheet material reduces the temperature of superplastic forming (SPF) by 200°C and of diffusion bonding (DB) by 100°C, compared to the conventional superplastic forming Ti-6Al-4V material with microcrystalline structure (grain size 3 μm). Unlike commercially available sheet, the submicron grained sheet is characterised by isotropic formability. Submicrocrystalline processed Ti-6Al-4V sheet can be successfully used in SPF/DB technology. The temperature range of superplastic forming can be between 700 and 800°C, and diffusion bonding at 800°C.
A Ti–6Al–4V alloy sheet with a submicrocrystalline structure (grain size of 0.3
μm) was produced by multistep isothermal forging followed by flat rolling at temperatures below 650°C. The sheet showed ...a very strong basal texture and isotropic properties in the sheet plane. Room temperature yield strength, ultimate tensile strength, and fatigue limit of the sheet were 1.2–1.3 times higher than that of sheet with micron-sized grains. Sheet with the submicrocrystalline structure showed superplastic properties at temperatures 650–750°C. A complex hollow structure was produced from the sheet by diffusion bonding/superplastic forming at temperatures 750–800°C. The structure had high microstructural homogeneity and high quality of diffusion bonding.
The superplastic behavior of extremely fine-grained (300 nm) Ti–6Al–4V was studied by performing elevated temperature uniaxial tensile tests in the temperature range of 700–900
°C. The strain rate ...was varied from 10
−5 to 10
−1
s
−1 to estimate the value of the strain rate sensitivity coefficient,
m. The ductility of the fine-grained Ti–6Al–4V specimens was compared with that of a control set of conventional superplastic Ti–6Al–4V specimens with an average grain size of 3 μm. The results obtained indicate that the fine grain sized materials should see application in commercial use, with the caveat that a 1-μm grain size is considered optimum in terms of the superplastic forming temperature and subsequent creep behavior at use temperature.
Laminated composite materials consisting of an orthorhombic Ti
2
AlNb based alloy and an (α+β) titanium alloy have been fabricated at a laboratory scale using a two-step process involving diffusion ...bonding and hot rolling. The feasibility of fabrication of two and three layered materials with high quality bonding between layers was demonstrated. Preliminary assessment of the tensile mechanical properties of the obtained composite materials showed that they were superior to those of the titanium alloy and slightly inferior to the orthorhombic alloy.
The review analyzes variability of clinical manifestations of p.Arg870His in the MYH7 gene, which is repeatedly registered in patients with hypertrophic cardiomyopathy (HCM). The analysis involves ...the data from scientific publications obtained as a search result in the PubMed, СlinVar, and eLibrary.ru databases, as well as authors’ own results. A wide range of phenotypic manifestations have been revealed in carriers of p.Arg870His, from the asymptomatic to severe course, rapid progression, and early death. The review considers possible factors that modify the effect of the pathogenic variant (i.e. dosage of the pathogenic variant, the presence of other unfavorable genetic variants, etc.). The importance of accumulating information on the clinical features of HCM in the carriers of specific gene variants is emphasized in order to clarify their pathogenicity and to identify factors modifying the clinical outcome, which is important for the choice of the treatment strategy for HCM.
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