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Gazizov M.,Belgorod State University | Teleshov V.,All Russia Institute Of Light Alloys | Zakharov V.,All Russia Institute Of Light Alloys | Kaibyshev R.,Belgorod State University
Journal of Alloys and Compounds | Year: 2011

The solidification behaviour and structural evolution during homogenisation annealing of a 0.17 mass% Sc and 0.1 mass% Ge modified Al-Cu-Mg-Ag alloy was examined. The formation of the primary Mg 2Ge phase and the Sc-enriched θ-phase (Al 2Cu) was found to occur under solidification; no evidence for the formation of the ternary W-phase (Al 8-xCu 4+xSc) was observed. Approximately 70% of the overall Sc content is fixed in the supersaturated solid solution. However, only two thirds of this Sc is consumed by the formation of a dispersion of nanoscale Al 3Sc particles within the Al matrix under homogenisation annealing. A third of the Sc is consumed by the formation of the W-phase because of Sc diffusion into the primary θ-phase, which leads to its transformation into the W-phase. Finally, the W-phase consumes ∼50% of the overall Sc content. No effects of homogenisation annealing on the volume fraction of Mg 2Ge were observed. The optimal chemical composition of alloys in the Al-Cu-Mg-Ag-Sc system is discussed. © 2011 Elsevier B.V.

Filatov Yu.A.,All Russia Institute Of Light Alloys
Tsvetnye Metally | Year: 2014

Strength of aluminium alloys of Al - Mg - Sc system is considerably higher than strength of Al - Mg alloys with the same content of Mg, saving their basic advantages, such as: good weldability, high corrosion resistance and absence of necessity in reinforcing heat treatment. There is described the mechanism of hardening of Al - Mg system alloys during their scandium alloying. There are considered the following types of Al - Mg - Sc alloys: - high-alloy type, containing >4% of Mg (01570, 1570C and 1545K grades); - low-alloy type, with addition of <4% of Mg (01523, 01515, 01513, 01511 and 01411 grades). Mechanical properties of sheets and plates, made of high Al -Mg - Sc system alloys, are given together with characteristics of sheets' weldability, and structure and properties of basic metal and welded joints. There is shown the possibility of obtaining of welded joints, which are practically equally strength to annealed basic metal. There are given the examples of possible application of high Al - Mg - Sc alloys both in high-strength hermetical welded constructions (space vehicle frame, fuel tanks, containers for transportation of liquefied natural gas) and in load-bearing welded construction, intended for working in adverse climatic conditions and in distant Far North regions. There is shown the possibility of usage of low Al - Mg - Sc system alloys for production of the following constructions: - welded constructions with high corrosion and radiation resistance; - heat-conducting welded constructions with increased strength; - brazed constructions, obtained by methods of high-temperature vacuum soldering.

Results are presented for a study of non-dendritic solidification of light alloys based on an accomplished scientific discovery. © 2010 Springer Science+Business Media, Inc.

Merkulova S.M.,All Russia Institute Of Light Alloys | Bochvar S.G.,All Russia Institute Of Light Alloys
Tsvetnye Metally | Year: 2016

There was set a certain range of tasks for the products manufacturing with a required (given) level of properties and, as a result, with optimal structure, which may be solved with the lower costs, with application of cheaper technologies. This article is devoted to the development of the sufficiency principle (for example: cooling rate during crystallization). As applied to the high-strength deformed alloys, the main point of this principle shows the fact that reaching the cooling rate, where the primary crystallization of intermetallides is successfully pressed, makes its following increasing unsuitable, if it requires the additional costs. Significant grinding of primary silicon crystals and other proeutectoid constituents is possible due to the complex modifying processing, combining the introduction of active modifiers, and cavitation processing of melt. This is called a principle of cooling ratio sufficiency. Scandium content in alloys may be decreased during the alloying process due to the introduction of transition and rare-earth metals, saving the set level of properties. This is called a sufficiency principle in the alloying process. In certain cases, increased modification, leading to the significant grinding of grains, has a range of disadvantages. In this case, there was found the decreasing of mechanical properties of pressed products.

Zakharov V.V.,All Russia Institute Of Light Alloys
Metal Science and Heat Treatment | Year: 2012

Topics of modification of the grain structure and of formation of supersaturated solid solution in crystallization of melts of scandium-alloyed aluminum alloys are considered. The strong modifying property of scandium is a result of the effective inoculating action of Al 3Sc particles and their great number in unit volume of the melt. Scandium is susceptible to formation of supersaturated solid solutions at enhanced crystallization rates, and an additive of zirconium intensifies this susceptibility. © 2012 Springer Science+Business Media, Inc.

Zakharov V.V.,All Russia Institute Of Light Alloys
Metal Science and Heat Treatment | Year: 2015

C-curves of isothermal decomposition of the solid solution of scandium in aluminum are plotted for binary Al – Sc alloys with different scandium content. It is shown that growth in the scandium content from 0.14 to 0.55% reduces the incubation period by 2 – 3 orders of magnitude and increases the rate of the decomposition by 2 orders of magnitude. The causes of the accelerated decomposition of the solid solution of scandium in aluminum are discussed. © 2015, Springer Science+Business Media New York.

Elagin V.I.,All Russia Institute Of Light Alloys | Zakharov V.V.,All Russia Institute Of Light Alloys
Metal Science and Heat Treatment | Year: 2013

Development of aluminum alloys with lithium additives is analyzed since the 1960s until present. A detailed description of alloys of the Al - Mg - Li and Al - Cu - Li systems is presented, their advantages, disadvantages and prospects of application are analyzed. © 2013 Springer Science+Business Media New York.

Merkulova S.M.,FCS HT SNPO Eleron | Bochvar S.G.,All Russia Institute Of Light Alloys
Tsvetnye Metally | Year: 2016

Influence of ladle treatment of Al - Ti - B and Al - Ti - C systems on grain size of aluminium ingots made of A7 technical pure aluminium and A99 high pure aluminium is examined. This ladle treatment is based on usage of ultrasonic processing and modifying bars. It is shown that application of ultrasonic processing of melt flow using alloying composition with active origination particles allows to decrease essentially aluminium grain size. So, ladle treatment of A7 aluminium melt flow allowed to decrease grain size from 500 to 90 μm (grain is close to non-dendrite one). This result has been achieved during introduction of modifying bar (with composition Al - 5% Ti - 1% B, made by "Kawecki" company) in the area of developed cavitation, and with calculation of additional adding of 0.055% Ti. Investigation of A99 aluminium has displayed decrease of dendrite grain size from >2000 to 165 μm during introduction of modifying bar (with composition Al - 1.4% Ti - 0.15% C, made by VILS - All-Russian Institute of Light Alloys), without cavitation processing of melt flow, but with its ultrasonic processing. Decrease of dendrite grain size to 130 μm has been achieved during introduction of modifying bar of the same composition and with additional adding of 0.1% Ti. Introduction of additional origination nuclei from modifying bar of Al - Ti system was not finalized in such visible effect, though grain size has decreased by appr. 6 times. Complex ladle modifying of low- Alloyed AD31 alloy (having no Zr in its composition) allowed to obtain non-dendrite structure with 60 μm grain average size in the ingots of 60 mm diameter. It is shown that modern ultrasonic generators can provide stable operation at industrial casting temperatures practically for all aluminium alloys. At the same time, acoustic processing parameters (such as frequency, power and amplitude) don't vary during long time comparative with casting period for industrial alloys (with diameter up to 300 mm and length up to 1.5 m). It is concluded that forming of stable cavitation area in the melt near operating ultrasonic source is possible in the case when oscillation amplitude of an oscillator exceeds 10 μm for 18-22 KHz frequency.

Zakharov V.V.,All Russia Institute Of Light Alloys | Rostova T.D.,All Russia Institute Of Light Alloys
Metal Science and Heat Treatment | Year: 2014

The mechanism of hardening of deformed semiproducts from aluminum alloys upon the introduction of scandium into the latter is discussed. The hardening is explained by the presence of secondary dispersed particles of type Al 3 Sc and formation of a subgrain structure in the semiproducts. Growth in the strain in fabrication of the semiproducts is accompanied by noticeable intensification of the hardening effect of the scandium additive, which is associated with refinement of the grain structure. © 2014 Springer Science+Business Media New York.

Semenov A.M.,Gazprom | Siniavskiy V.S.,All Russia Institute Of Light Alloys
NACE - International Corrosion Conference Series | Year: 2015

Al-Li alloys form a new generation of aluminium alloys with unique construction parameters, namely, high static and dynamic strength, low density, high Young's modulus and satisfactory weldability. However resistance to stress corrosion cracking (SCC) and exfoliation corrosion in various corrosion aggressive environments are not completely understood. The purpose of the present work is to determine the resistance to SCC and to estimate exfoliation corrosion of the Al-Li alloys semiproducts in various environments. Samples were tested in different climate conditions: Barents Sea coast, Cuba island coast, Moscow industrial zone, sea tropics environment on board of the "Izumrud" vessel. In addition, laboratory corrosion studies have been carried out and electrochemical characteristics of industrial and experimental alloys have been determined. Sea tropics of the corrosion station on the Cuba island and of the Indian Ocean (specimens testing on board of the scientific vessel "Izumrud") are established to be the most aggressive corrosion environments, and the threshold stress for stress corrosion cracking equals 150 MPa. The least aggressive corrosion environments are Moscow industrial zone and Barents littoral sea - the threshold level of stresses at stress corrosion cracking equals 250 MPa. Laboratory tests for stress corrosion cracking resistance well correlates the results obtained in the sea tropics environment. During corrosion cracking cracks predominantly have inter-crystalline crack propagation. But the fracture in the mechanical break zone significantly differs from traditional 2xxx and 7xxx series alloys. The fracture behavior of propagation the crack in this zone changes to trans-crystalline. Al-Li alloys have a good exfoliation corrosion resistance level in all the environments. © 2015 by Nace International.

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