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Shvartsburg A.B.,Far Eastern Federal University | Obod Y.A.,Mf Stelmakh Research Institute Polus | Kuzmichev A.I.,Kharkiv Polytechnic Institute | Volpian O.D.,Mf Stelmakh Research Institute Polus | Parkhomenko Y.N.,National Research and Technological University
Optical Materials Express | Year: 2014

The technology of fabrication of gradient dielectric nanofilms with the predesigned distribution of refractive index by means of magnetron sputtering of the nanofilm components on the movable substrate, based on the prescribed motion of substrate, is presented. The theoretical prediction of giant controllable heterogeneity-induced dispersion of gradient dielectric periodical nanostructures without free carriers is verified by the experimental measurements of their transmittance in visible and near infrared spectral ranges. The unusual transmittance spectra of these structures are distinguished by strong dispersion nearby the red edge of visible range and almost constant high transmittance in the near infrared range. Method of non-destroying control of gradient optical nanolayers, using the X-ray reflectometry of their density distribution, is developed, and the possibility of formation of nanocluster structures of these layers is shown. Potential of periodical gradient all-dielectric nanostructures for flexible design and fabrication of broadband antireflection coatings with sub-wavelength thicknesses is considered. © 2014 Optical Society of America. Source


Belov N.A.,National Research and Technological University | Alabin A.N.,National Research and Technological University | Matveeva I.A.,UC Rusal
Journal of Alloys and Compounds | Year: 2014

The possibility to use alloys of the Al-Cu-Mn-Zr-Sc system for obtaining rolled sheets directly from cast ingots (without homogenization process) was investigated. The experimental (SEM, TEM, EMPA, and mechanical tests) study and Thermo-Calc software simulation were used for alloy composition optimization. It was shown that optimal structure could be developed in the alloys of the following compositional range: 1-2% Cu, 1-2% Mn, ∼0.2% Zr and ∼0.1% Sc (wt%). Such nearly single-phase structure achieved in the as-cast state provides high ductility of the alloys and allows for up to 87% hot rolling reduction and up to 75% cold rolling reduction without intermediate annealing. Experimental Al-Cu-Mn-Zr-Sc and commercial AA2219 alloys were compared. Tensile tests of 0.5 mm sheets proved the advantage of the experimental alloy. Although the AA2219 alloy can be considerably hardened upon quenching and aging (T6), this hardening effect completely disappears after short-term heating at 300-350 C. On the other hand the experimental alloy was thermally stable due to the formation of polygonized structure, which resulted from large amount of Al 20Cu2Mn3 and Al3(Zr,Sc) (L1 2) dispersoids that effectively pinned down dislocations. No secondary Al2Cu precipitates were detected. Such structure is the most favorable for creep resistance as Mn- and Zr-containing dispersoids have a higher thermal stability than Al2Cu precipitates. Proposed range of compositions can be recommended for the development of new aluminum wrought alloys, which will have two main advantages as compared with commercial alloys of the AA2219 type: (1) high tolerance to heating up to 350 C because of high amount Al3(Zr,Sc) and Al20Cu2Mn dispersoids; (2) energy efficient processing, in particular due to the elimination of homogenization, solution treatment and quenching. © 2013 Elsevier B.V. All rights reserved. Source


Belov N.A.,National Research and Technological University | Naumova E.A.,Moscow State Technical University | Alabin A.N.,National Research and Technological University | Matveeva I.A.,UC Rusal
Journal of Alloys and Compounds | Year: 2015

Abstract The phase composition, structure and hardening of alloys in the aluminium corner of the Al-Ca-Sc system were studied in the range up to 10% Ca and up to 1% Sc. The experimental study (optical, scanning and transmission electron microscopy with electron-microprobe analysis, differential thermal analysis and hardness measurements) was combined with Thermo-Calc software simulation for the optimization of the alloy composition. It was shown that only phases of the binary systems (Al4Ca N Al3Sc) might be in equilibrium with the aluminium solid solution. It was shown that the (Al)+ Al4Ca eutectic had a much finer structure as compared with the Al-Si eutectic, which suggests a possibility of reaching higher mechanical properties as compared to commercial alloys of the A356 type. The influence of the annealing temperature within the range up to 600 °C on the structure and hardness of the Al-Ca-Sc experimental alloys was studied. It was determined that the maximum hardening corresponded to the annealing at 300 °C, which was due to the precipitation of Al3Sc nanoparticles with their further coarsening. With an example of an Al-7.6% Ca-0.3% Sc model experimental alloy, a principal possibility of manufacturing aluminium casting alloys based on the (Al)+ Al4Ca eutectic was demonstrated. Unlike commercial alloys of the A356 type, the model alloy does not require quenching, as hardening particles are formed in the course of annealing of casting. © 2015 Elsevier B.V. Source


Belov N.A.,National Research and Technological University | Alabin A.N.,National Research and Technological University
Materials Science Forum | Year: 2013

The possibility of using alloys of the Al-Cu-Mn-Zr system for obtaining cold rolled sheets directly from cast billets (without homogenization) was investigated. The experimental (SEM, TEM, DSC, mechanical tests, etc.) study and Thermo-Calc software simulation were used for alloy composition optimization. It was shown that optimal structure could be developed in alloys of the following compositional range: 1-2% Cu, 1-2% Mn and 0.2-0.6% Zr. The proposed range of compositions can be recommended for development of new aluminium wrought alloys, which will have two main advantages compared with the commercial alloys of the AA2219 type: i) high tolerance to heating up to 300 °C because of the high amount of Al3Zr and Al20Cu2Mn dispersoids; ii) energy efficient processing, in particular due to the elimination of homogenization, solution treatment and quenching. © (2013) Trans Tech Publications, Switzerland. Source


Belov N.A.,National Research and Technological University | Alabin A.N.,National Research and Technological University
Materials Science Forum | Year: 2014

Principles of optimization of the phase constitution of a new group of aluminum alloys, i.e., sparingly alloyed high-strength casting nickalyns are considered. The Thermo-Calc software and experimental methods (LM, SEM, TEM, EPMA, etc.) were used for analyzing the phase constitution of the Al-Zn-Mg-Cu-Fe-Ni system as applied to high-strength (UTS>450 MPa) aluminum alloys based on (Al)+Al3Ni and (Al)+Al9FeNi eutectics. Both eutectics possess the fine structure but the latter is more expedient due to the lower content of nickel. Then the iron becomes an alloying component rather than a harmful impurity. It is shown that the addition of copper substantially complicates the phase constitution and strongly decreases the equilibrium solidus, which limits the possibility of carrying out the high temperature annealing. This can negatively affect the spheroidization of the Al3Ni and Al9FeNi phases. A set of calculated and experimental data is used to show the perspectives of replacement of the existing high-strength casting aluminum alloys based on Al-Cu system (AA201, 206, 224) by the sparingly alloyed low-copper weldable nickalyn Al6Zn0.5Ni. © (2014) Trans Tech Publications, Switzerland. Source

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