Thermal Stability and Mechanical Properties of 5483 Al Alloy Processed by ECAP

Equal Channel Angular Pressing (ECAP) is one of the methods which allows to obtain ultrafine-grained and nanocrystalline metallic materials. It is well known that microstructure of materials pro-cessed by ECAP in not very stable. There were published many experimental and theoretical evidences of this fact obtained by various methods such as microstructure observations, properties measurement and computer modeling. The aim of presented paper was to investigate the thermal stability of microstructure and mechanical properties of the Al 5483 alloy processed by ECAP. As a result of performed investigations it was concluded that accumulated plastic deformation has no influence on the thermal stability of Al 5483 alloy processed by ECAP. It was also found that properly chosen parameters of ECAP and subsequent annealing allows to produce materials with high strength and plasticity. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3543

Relationship Between Masticatory Efficiency and Occlusal Parameters Established in T-Scan II System

The aim of this investigation was to establish possible correlation between parameters of occlusion and masticatory efficiency. MATERIAL: Data were obtained in 15 healthy persons, 23-31 years of age (mean 25 years) with correct own dentition and without any disturbances of the stomatognathic system. METHODS: Masticatory efficiency was measured using Optosil test modified by Slagter et al. after 20 and 80 cycles of chewing. It the time of chewing for 20 and 80 cycles of chewing was also established. Analysis of occlusion was made using T-scan II computerized system. Registration of occlusion was obtained before measuring masticatory efficiency after 20 and 80 cycles of chewing. Statistical analysis was made and p<0.05 was statistically significant. RESULTS: The time of chewing for 20 cycles and for 80 cycles respectively, mean 16 s +/- 3.0, and 55.6s +/- 9.5) reduction of particle size was about 1.5 mm. Time to maximal force ofpressure was shorter when chewing was longer. Maximal force of pressure for a unit of deflection indicator surface was higher after chewing. Share of sides of the teeth arch was about 59 per cent in all measurements. Maximal force of pressure for a unit of deflection indicator surface was correlated with the time of chewing for 20 cycles of chewing (p <0.05). Correlation of time from the first contact of teeth to maximal force of pressure and maximal force of pressure for a unit of deflection indicator surface was statistically significant for 80 cycles . There was no evident correlation between values of X50 and occlusal parameters established in computerizedanalysis. CONCLUSION: Chewing ability is correla ted with occlusion although this relationship is not significant

Stable or improved neurological manifestations during miglustat therapy in patients from the international disease registry for Niemann-Pick disease type C: an observational cohort study

Background: Niemann-Pick disease type C (NP-C) is a rare neurovisceral disease characterised by progressive neurological degeneration, where the rate of neurological disease progression varies depending on age at neurological onset. We report longitudinal data on functional disease progression and safety observations in patients in the international NPC Registry who received continuous treatment with miglustat. Methods: The NPC Registry is a prospective observational cohort of NP-C patients. Enrolled patients who received ≥1 year of continuous miglustat therapy (for ≥90 % of the observation period, with no single treatment interruption >28 days) were included in this analysis. Disability was measured using a scale rating the four domains, ambulation, manipulation, language and swallowing from 0 (normal) to 1 (worst). Neurological disease progression was analysed in all patients based on: 1) annual progression rates between enrolment and last follow up, and; 2) categorical analysis with patients categorised as 'improved/stable' if ≥3/4 domain scores were lower/unchanged, and as 'progressed' if <3 scores were lower/unchanged between enrolment and last follow-up visit. Results: In total, 283 patients were enrolled from 28 centers in 13 European countries, Canada and Australia between September 2009 and October 2013; 92 patients received continuous miglustat therapy. The mean (SD) miglustat exposure during the observation period (enrolment to last follow-up) was 2.0 (0.7) years. Among 84 evaluable patients, 9 (11 %) had early-infantile (<2 years), 27 (32 %) had late-infantile (2 to <6 years), 30 (36 %) had juvenile (6 to <15 years) and 18 (21 %) had adolescent/adult (≥15 years) onset of neurological manifestations. The mean (95%CI) composite disability score among all patients was 0.37 (0.32,0.42) at enrolment and 0.44 (0.38,0.50) at last follow-up visit, and the mean annual progression rate was 0.038 (0.018,0.059). Progression of composite disability scores appeared highest among patients with neurological onset during infancy or childhood and lowest in those with adolescent/adult-onset. Overall, 59/86 evaluable patients (69 %) were categorized as improved/stable and the proportion of improved/stable patients increased with age at neurological onset. Safety findings were consistent with previous data. Conclusions: Disability status was improved/stable in the majority of patients who received continuous miglustat therapy for an average period of 2 years

Microstructure and tensile behavior of Fe–16Al-based alloy after severe plastic deformation

International audienceThe applicability of three-axis plane-strain compression for grain refinement and improving the properties of iron aluminum alloy (Fe–16Al–5Cr–1Mo–0.1Zr at.%) has been studied. Particular attention was paid to evolution of the microstructure with respect to effective strain and mechanical properties under tensile load, as well as the factors that influence cracking. The obtained results showed that the multi-axis compression in the MaxStrain system, as a method of severe plastic deformation, is capable of refining the grain size in the Fe–16Al–5Cr–1Mo–0.1Zr (at.%) alloy to about 500 nm without affecting significantly the initial shape of the specimen with constrained ends. The deformation of the investigated alloy at RT with the strain to 2.7 is not enough to form an ultrafine-grained structure. This kind of homogeneous structure could only be obtained through the high temperature (600 °C) processing with a very large strain ( = 30.0). The ultrafine-grained structure was formed after deformation at 600 °C with the application of 67 passes ( = 30), and exhibited high ultimate tensile strength (UTS 880 MPa) with an elongation to failure of about 0.8%. In addition, it demonstrated a dimple fracture that was in contrast to its micro-sized grained counterparts with moderate UTS (550–750 MPa) and good elongation to failure (6–9%), but brittle fracture

Use of micro tensile test samples in determining the remnant life of pressure vessel steels

The aim of this collaborative study was to measure mechanical properties of 14MoV67-3 steel taken from small sections of material machined in-situ from an operating high pressure collector pipe after different operating lifetimes (from 0h to 186 000h) at elevated temperatures (540°C). Conventional methods of measuring mechanical properties of materials, such as the uniaxial tensile test require relatively large test samples. This can create difficulties when the amount of material available for testing is limited. One way of measuring mechanical properties from small quantities of material is using micro tensile test samples. In this work, micro-samples with a total length of 7.22mm were used. Digital Image Correlation method (DIC) was employed for the strain measurements in a uniaxial tensile test. This paper shows that there is measurable difference in the yield, ultimate tensile strength and elongation to failure as a function of the plant operating conditions. This work demonstrates, therefore, a ‘semi-invasive’ method of determining uniaxial stress-strain behaviour from plant components