To the 75th Anniversary of Ilya I. Novikov, Professor
Superplasticity
Novikov I.I., Portnoi V.K. Features of superplastic deformation of some aluminum alloys
A group of superplastic D20, D19, AMg4, and Neopral aluminum alloys, which are characterized by high superplastic properties at temperatures near solidus, has been studied. They differ from other superplastic aluminum alloys (for example, 7475 alloy of the system Al-Zn-Mg-Cu) in low contribution of grain boundary sliding (7–20 %) that is not characteristic for the majority of similar alloys. Working mechanisms in this group of superplastic aluminum alloys are found to be intragranular dislocation sliding and diffusion creep, which are to result in extension of grains in the direction of deformation. This picture was observed in our experiments to the same degree as in other alloys. Qualitative analysis of the grain shape and sizes under superplastic deformation of the studied alloys showed that insufficient grain boundary sliding is compensated by dynamic recrystallization to lead in dividing the extended grains in parts and generating new ones.
Kaibyshev O.A., Zaripov N.G. Superplasticity in metals and ceramics
Generality and differences in mechanisms of superplastic deformation are analyzed between metallic and ceramic materials. Superplastic deformation is established to be dependent on the properties of grain boundary structure and defined by their extension in a polycrystal. A specific deformation mechanism, i.e. cooperative grain boundary sliding, functions under the optimal temperature-velocity conditions. The mechanisms of cooperative grain boundary sliding band formation are considered by the examples of aluminum tricrystals, Zn-22%Al alloy, and Bi2O3 based ceramics. It was shown on the basis of the analysis of the experimental data that the same deformation mechanism defines the generality of suprplastic deformation in metals and ceramics. Nevertheless the differences arise at sharp change in deformation mechanism, in particular as a result of liquid phase formation along the grain boundaries.
Smirnov O.M., Ershov A.N., Tsepin M.A. Rheological behavior of superplastic nanocrystalline and amorphous materials
Demonstrating structural superplasticity as compared with crystallized metallic melts and amorphous materials, rheological behavior of metallic and ceramic materials is analyzed. The rheological state of the materials varies from tough to tough-plastic one. Superplasticity at high deformation rates and low values of shear viscosity being peculiar to the materials is considered as enough prospecting for development of new metal forming processes.
Kaibyshev R.O., Musin F.F. Features of superplastic deformation of 5083+0.2 % Zr aluminum alloy at pre-melting temperatures
The superplastic properties and microstructural evolution of a modified 5083 + 0.2 % Zr aluminum alloy with an initial grain size of 6.2 m m were examined in the temperature range of 500-580 oC and strain rates ranging from 10-5 up to 10-1 s-1. On the basis of the results obtained the increase in deformation temperature up to 570 oC (~0.99Tm) is shown to lead to significant changes in superplastic behavior of the alloy. Such a type of the behavior is characterized by the lack of threshold stresses, extension of an optimal interval of superplasticity towards lower strain rates, and activation energy for superplastic flow being higher than for lattice diffusion in aluminum. Mechanisms of superplasticity at pre-melting temperatures of the alloy are discussed.
Physical Metallurgy and Heat Treatment of Aluminum Alloys
Davydov V.G. On some urgent problems of development of aluminum alloys and processes for aerospace application
The evolution of requirements to structural aluminum alloys of aerospace destination is considered. Lithium and scandium alloyed aluminum alloys are shown to keep their nature as highly prospecting materials for crucial structures. Industrial application of second-generation alloys of a higher complex of specific strength and service life characteristics should be executed with taking special melting and casting practice, plastic strain, and heat treatment into consideration. An analysis of a series of technological problems that require carrying out complex investigations, such as thermal stability of alloys, anisotropy of properties of semiproducts, and others, has been made.
Zakharov V.V., Rostova T.D. On the effect of dispersed Al3Li and Al3Sc particles to be cut by dislocations on properties of aluminum alloys
Secondary particles of metastable d ’(Al3Li) and stable Al3Sc phases enter the phase composition of aluminum alloys that contain lithium and scandium as alloying components. The particles are of spherical shape and entirely coherent to the aluminum matrix till reaching certain sizes. They can be cut by sliding dislocations. Presence of d ’(Al3Li) particles or preliminary precipitation of these phases having long range ordering furthers the localization of deformation at plastic working and in the course of mechanical tests of specimens. This feature noticeably affects the technological plasticity of alloys, the level and nature of anisotropy of mechanical properties of heat-treated semiproducts.
Zolotarevsky V.S., Lainer I.S., Belov N.A. Low-cycle fatigue of cast aluminum alloys
Endurance life of commercial and experimental cast alloys on the basis of the systems Al-Si-Cu-Mg, Al-Cu-Mn, Al-Zn--Ni-Mg-Cu, and Al-Ni-Zr-Cr was determined at the room temperature and T = 150 oC under the conditions of low-cycle fatigue with s max = 250 MPa. The phase composition and microstructure was shown to affect noticeably and ambiguously the low-cycle fatigue. In many cases the low-cycle fatigue values poorly correlate with static mechanical properties.
Alloys of Non-Ferrous Metals
Rytvin E.A., Tykochinsky D.S., Yastrebov V.A. Dispersion-hardened platinum and its alloys
Production processes and main properties of platinum-based dispersion-hardened materials developed in “Supermetall” NPK, Moscow are considered. Original process comprising dispersing alloys with zirconium additives and internal oxidation makes it possible to produce enough practically feasible materials of high properties of heat-resistance and corrosion resistance. The microstructure, morphology, and distribution of hardening oxides in dispersion-hardened platinum alloys and their stability are studied using structural analyses (optical and electron microscopy, X-ray analysis).
Kolachev B.A., Ilyin A.A., Nosov V.K. Possibilities and prospects of hydrogen technology of titanium alloys
The paper gives a review of the main regularities related to the effect of hydrogen on structure, technological, and physical-mechanical properties of titanium alloys. Some effects related to alloying of titanium alloys by hydrogen can be used for improvement of the production and treatment processes as well as for improving their mechanical properties.
Polkin I.C. Technology of the future is complete process monitoring
Possibilities to create the monitoring of production process of semiproducts with improved mechanical properties were considered by the example of high-strength VT22 titanium alloy. The monitoring organization is shown to require profound knowledge and actual results of studies over the whole of stages related to the process conversion. Expenditures for the monitoring organization can be repaid at the cost of improving quality of the products produced. The monitoring organization of the manufacture enters the requirements of ISO 9000-2000 as “Total Quality Management”.
Rokhlin L.L., Bochvar N.R., Lysova E.V. The effect of impurities and structural state on ability of copper to plastic deformation
The effect of composition and heat treatment on structure and properties of rods and wires made of two copper grades (M1 and M0b) after hot rolling and drawing at room temperature and deformation of about 95-99.99 % has been studied. Mechanical properties of rods and wires were measured at room and high temperatures as well as hardness, microporosity, specific and residual electrical resistivity were found after deformation and the following heat treatment. Precipitation of impurities out of copper solid solution at T = 400–600 oC and their reverse dissolving were established after high annealing temperatures. The onset of recrystallization temperature of copper wire at different stages of cold drawing was determined.
Pyshmintsev I.Yu., Mikhailov S.B., Khotinov V.A., Popov A.A. Mechanical properties and effects of internal friction in cold-rolled ultra-finegrained VT1-0 alloy
Structure and properties of VT1-0 alloy subjected to equichannel angular press forming and cold rolling have been studied. A comparative analysis of mechanical properties, amplitude-dependent internal friction, and alloy structure in large-grain cold-rolled state was carried out. It was shown that ultrafine-grained structure providing for high properties is formed under equichannel angular press forming. Distinctive features of structural changes in cold-rolled ultrafine-grained alloy were found during successive isochronous annealing processes. The effects of amplitude-dependent internal friction, which reflects changing the mobility of dislocation group and the level of residual stresses in ultrafine-grained state during annealing, were found.
Akimov I.I., Vorobieva A.E., Pantsyrny V.I., Shikov A.K. Superplastic materials on the VTSP basis: production process, properties, prospects
A brief review of present-day developments in the field of technical superconducting materials on the basis of high-temperature superconducting compounds abroad and in Russia is rendered. Examples of application of high-temperature superconducting materials when developing electric devices are given.
