Microstructure, texture, and mechanical properties of magnesium alloy WE43 processed by equal-channel angular pressing (ECAP) were investigated. Grain refinement down to 0.7–1µm and a transformation ...of texture from the basal to the prismatic one induced by ECAP were shown to lead to increased strength combined with enhanced ductility.
The effect of two-stage equal-channel angular pressing (ECAP) on the microstructure, the texture, and the mechanical properties of an MA2-1hp magnesium alloy is analyzed. ECAP leads to the formation ...of a submicrocrystalline structure with an average grain size of 640 nm, which includes Mg
17
Al
12
phase particles with an average grain size of 240 nm and a volume fracture of 5.5%. A scattered tilted basal texture forms after ECAP, and its experimental pole figures are used for calculating orientation distribution functions and determining the volume fractions of the main orientations and the Schmid factors for different deformation systems. An increased activation of basal slip is found after both the first and the second stages of ECAP. As a result of two-stage ECAP, the strength properties of the alloy that correspond to the minimum acceptable values achieved by direct compression are obtained. Ductility is 44 and 18% after the first stage of ECAP plus subsequent annealing and after the second stage, respectively, which is almost four and two times higher than the initial value. The resulting strength mechanical properties of the alloy after the first and the second ECAP stages are analyzed using the Hall-Petch relation.
Objective: We hypothesized that very low birth weight (VLBW) infants have reduced serum and red blood cell (RBC) selenium (Se) at birth, which decrease further with current nutrition and are ...associated with chronic lung disease and septicaemia. Design: We studied Se intake, concentration in serum and RBCs and glutathione peroxidase (GSH-Px) activity in preterm and term infants from birth until 16 weeks. Data are meanstandard deviation (s.d.). Setting: Seventy-two preterm infants in two groups, born in Berlin, gestational age 26+0/30+0 weeks, birth weight 845/1270 g, with low Se intake (2.20.8/2.51.2 g/kg/day), and 55 term infants, gestational age 39+1 weeks, birth weight 3160 g, born in Venezuela (high Se intake: 298 g/day). Results: A balance study in 10 preterm infants showed that Se is well absorbed from human milk (779%). Serum concentration was higher in term (142.040.0 g/l) than in preterm infants (17.88.1/19.92.2 g/l) at 4/7 weeks. Serum and RBC concentration of Se declined in all infants, low values in preterm infants did not correlate with chronic lung disease and septicaemia. GSH-Px activity in RBCs remained stable until 6 weeks of age in all infants and was not correlated with Se in RBCs. Conclusions: Se concentration in serum decreases during the first weeks of life and depends on intake. GSH-Px activity is not useful as a marker for Se status in infants up to 16 weeks after birth.
Euro+Med-Checklist Notulae, 11 VON RAAB-STRAUBE, ECKHARD; RAUS, THOMAS
Willdenowia,
12/2019, Letnik:
49, Številka:
3
Journal Article
Recenzirano
Odprti dostop
This is the eleventh of a series of miscellaneous contributions, by various authors, where hitherto unpublished data relevant to both the Med-Checklist and the Euro+Med (or Sisyphus) projects are ...presented. This instalment deals with the families Anacardiaceae, Asparagaceae (incl. Hyacinthaceae), Bignoniaceae, Cactaceae, Compositae, Cruciferae, Cyperaceae, Ericaceae, Gramineae, Labiatae, Leguminosae, Orobanchaceae, Polygonaceae, Rosaceae, Solanaceae and Staphyleaceae. It includes new country and area records and taxonomic and distributional considerations for taxa in Bidens, Campsis, Centaurea, Cyperus, Drymocallis, Erigeron, Hoffmannseggia, Hypopitys, Lavandula, Lithraea, Melilotus, Nicotiana, Olimarabidopsis, Opuntia, Orobanche, Phelipanche, Phragmites, Rumex, Salvia, Schinus, Staphylea, and a new combination in Drimia. Citation For the whole article: Raab-Straube E. von & Raus Th. (ed.) 2019: Euro+Med-Checklist Notulae, 11 Notulae ad floram euro-mediterraneam pertinentes No. 40. – Willdenowia 49: 421–445. doi: https://doi.org/10.3372/wi.49.49312 For a single contribution (example): Strid A. 2019: Bidens alba (L.) DC. – Pp. 424–426 in: Raab-Straube E. von & Raus Th. (ed.), Euro+Med-Checklist Notulae, 11 Notulae ad floram euro-mediterraneam pertinentes No. 40. – Willdenowia 49: 421–445. doi: https://doi.org/10.3372/wi.49.49312 Version of record first published online on 6 December 2019 ahead of inclusion in December 2019 issue.
Millimetron is a Russian-led 12 m diameter submillimeter and far-infrared space observatory which is included in the Space Plan of the Russian Federation for launch around 2017. With its large ...collecting area and state-of-the-art receivers, it will enable unique science and allow at least one order of magnitude improvement with respect to the Herschel Space Observatory. Millimetron will be operated in two basic observing modes: as a single-dish observatory, and as an element of a ground-space very long baseline interferometry (VLBI) system. As single-dish, angular resolutions on the order of 3 to 12 arc sec will be achieved and spectral resolutions of up to a million employing heterodyne techniques. As VLBI antenna, the chosen elliptical orbit will provide extremely large VLBI baselines (beyond 300,000 km) resulting in micro-arc second angular resolution.
This is the thirteenth of a series of miscellaneous contributions, by various authors, where hitherto unpublished data relevant to both the Med-Checklist and the Euro+Med (or Sisyphus) projects are ...presented. This instalment deals with the families Amaryllidaceae (incl. Alliaceae), Apocynaceae, Caryophyllaceae, Chenopodiaceae, Compositae, Crassulaceae, Cucurbitaceae, Gramineae, Hydrocharitaceae, Iridaceae, Labiatae, Liliaceae, Malvaceae, Meliaceae, Myrtaceae, Orobanchaceae, Oxalidaceae, Papaveraceae, Pittosporaceae, Primulaceae (incl. Myrsinaceae), Ranunculaceae, Rhamnaceae, Rubiaceae, Solanaceae and Umbelliferae. It includes new country and area records and taxonomic and distributional considerations for taxa in Allium, Anthemis, Atriplex, Centaurea, Chasmanthe, Chenopodium, Delphinium, Digitaria, Elodea, Erigeron, Eucalyptus, Hypecoum, Leptorhabdos, Luffa, Malvaviscus, Melia, Melica, Momordica, Nerium, Oxalis, Pastinaca, Phelipanche, Physalis, Pittosporum, Salvia, Scorzoneroides, Sedum, Sesleria, Silene, Spartina, Stipa, Tulipa and Ziziphus, new combinations in Cyanus, Lysimachia, Rhaponticoides and Thliphthisa, and the reassessment of a replacement name in Sempervivum. Citation For the whole article: Raab-Straube E. von & Raus Th. (ed.) 2021: Euro+Med-Checklist Notulae, 13 Notulae ad floram euro-mediterraneam pertinentes No. 42. – Willdenowia 51: 141–168. For a single contribution (example): Kunev G. 2021: Allium melanogyne Greuter. – Pp. 142–143 in: Raab-Straube E. von & Raus Th. (ed.), Euro+Med-Checklist Notulae, 13 Notulae ad floram euro-mediterraneam pertinentes No. 42. – Willdenowia 51: 141–168. Version of record first published online on 30 April 2021 ahead of inclusion in April 2021 issue.
The fracture behavior of
Cu
– 0.1%
Sn
alloy in samples of two types, namely with similar characteristics of ultra-fine-grained structure, but different in the second phase particle size has been ...investigated. These two types of samples were obtained by means of equal channel angular pressing with different number of passes. It has been found that with increase in the total strain the morphology and orientation of the fracture surface demonstrate changes corresponding to the development of shear mode. The arguments for the hypothesis that the fracture behavior change is connected with the decrease of the particle size and increase of their distribution density are given.
Long-length ultrafine-grained (UFG) Ti rods are produced by equal-channel angular pressing via the conform scheme (ECAP-C) at 200°C, which is followed by drawing at 200°C. The evolution of ...microstructure, macrotexture, and mechanical properties (yield strength, ultimate tensile strength, failure stress, uniform elongation, elongation to failure) of pure Ti during this thermo-mechanical processing is studied. Special attention is also paid to the effect of microstructure on the mechanical behavior of the material after macrolocalization of plastic flow. The number of ECAP-C passes varies in the range of 1–10. The microstructure is more refined with increasing number of ECAP-C passes. Formation of homogeneous microstructure with a grain/subgrain size of 200nm and its saturation after 6 ECAP-C passes are observed. Strength properties increase with increasing number of ECAP passes and saturate after 6 ECAP-C passes to a yield strength of 973MPa, an ultimate tensile strength of 1035MPa, and a true failure stress of 1400MPa (from 625, 750, and 1150MPa in the as-received condition). The true strain at failure failure decreases after ECAP-C processing. The reduction of area and true strain to failure values do not decrease after ECAP-C processing. The sample after 6 ECAP-C passes is subjected to drawing at 200¯C resulting in reduction of a grain/subgrain size to 150nm, formation of (101¯0) fiber texture with respect to the rod axis, and further increase of the yield strength up to 1190MPa, the ultimate tensile strength up to 1230MPa and the true failure stress up to 1600MPa. It is demonstrated that UFG CP Ti has low resistance to macrolocalization of plastic deformation and high resistance to crack formation after necking.
•Influence of crystallographic orientation of aluminum monocrystals of grade A999.•Formation of a nanocrystalline structure subjected to shock waves was investigated.•Used the shock front propagates ...in at pressures of 40 GPa and 50 GPa.•Effect of crystallographic orientation from the action of shock waves.
In this work, the influence of the crystallographic orientation of high-purity aluminum single crystals of grade A999 on the transformation of the initial structure as a result of exposure to shock waves at a temperature of −196°C was experimentally investigated. It was found that when the shock front propagates in the 110 direction at pressures of 40 GPa and 50 GPa, structural changes in aluminum single crystals are observed in the form of dislocation slip lines along the (111) and (110) planes. The impact of the shock front in the direction of 113 at a pressure of 50 GPa leads to coordination structural changes. It was found that a nanocrystalline structure with an average grain size of 80 nm is formed in the near-surface layers at a depth of 1–3 mm, and a subgrain structure is formed at a depth of 6–7 mm. In fact, a gradient type structure is formed. The reasons for the pronounced effect of the influence of the crystallographic orientation of high-purity aluminum single crystals on structural changes under the action of shock waves are discussed.
•A significant grain refinement of alloy Mg-1.0%Zn-0.3%Ca by ECAP was demonstrated.•A sharp inclined basal texture was formed by ECAP processing.•ECAP slightly increase the strength characteristic ...and fatigue life of the alloy.•Doubling of ductility due to the activation of prismatic slip was achieved by ECAP.•ECAP did not impair the chemical corrosion resistance of the alloy.
Magnesium alloy Mg-1.0%Zn-0.3%Ca was processed by equal channel angular pressing (ECAP) with the aim to refine its microstructure. ECAP was found to reduce the average grain size from 106.0 ± 2.05 μm in the initial state to 4.0 ± 0.19 μm and 8.0 ± 0.18 μm in the transverse and longitudinal sections, respectively. This resulted in a slight strengthening (the yield strength and the ultimate tensile strength rose from 92 and 194 MPa in the initial stat to 106 and 215 MPa after processing, respectively). The main advantage of ECAP is the concurrent increase of tensile elongation from 12.8% to 23.9%. The absence of pronounced strengthening and a significant increase in ductility are associated with the formation of an inclined basal texture, along with activation of prismatic slip during ECAP. It was also shown that ECAP leads to an increase in the fatigue limit of the alloy from 100 MPa to 110 MPa and does not impair its resistance to chemical corrosion.
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