Grain-boundary hardening in polycrystalline copper-based solid solutions

A study is made of the contribution of grain-boundary hardening to the overall hardening in a polycrystalline material on the basis of Ashby's model. Yield curves are used for copper-based solid solutions in polycrystalline and singlecrystal forms. It is shown that the contribution from statistically accumulated dislocations to the yield stress in a polycrystalline specimen reflects the behavior of the corresponding single crystal. The contribution from grain boundaries to the yield stress can be described in terms of the additional dislocation density due to the joint grain deformation in the aggregate up to high strains. At low strains, the main role in hardening of a polycrystalline material is played by the grain boundaries. This extends up to larger strains as the strain temperature is reduced and the alloy-element concentration increases.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 47–52, January, 1984.     

The Effect of Severe Plastic Deformation on the Structure and Mechanical Properties of Al–Mg–Li Alloys

The structural-phase state and mechanical properties of commercial aluminum alloys produced by severe plastic deformation are studied and compared to the initial polycrystalline state. This kind of treatment is found to give rise to the formation of a homogeneous ultrafine-grained structure with second-phase particles occurring predominantly along grain boundaries. With this structure, the strain-temperature and strain-rate intervals wherein the superplastic properties of the alloys under study are observed are shifted to lower temperatures and higher rates.     

Influence of boron on the low-temperature plasticity and fracture mechanism in the high-temperature synthesis of the intermetallic Ni3Al

We have studied the influence of boron on the plasticity and strength of the intermetallic compound Ni₃Al at stoichiometric and nonstoichiometric compositions, grown by self-propagating high temperature synthesis. We have determined the nature of the fracture and the fraction of brittle intercrystallite and viscous transcrystallite fracture. A correlation is found between the low temperature plasticity and the fraction of transcrystallite fracture. It is shown that the addition of boron, up to its solubility increases the cohesive strength of the grain boundaries in melts at the stoichiometric and nonstoichiometric compositions. In a melt with 25 at. % Al it remains about two times smaller than in a melt with 24 at. % Al.V. D. Kuznetsova Physicotechnical Institute at Tomsk University, Siberia. Institute for the Physics of Strength and Materials Fabrication, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 47–53, December, 1993.     

Structure,unelastic properties,and deformation behavior of ultrafine-grained titanium

The results of investigations into the structure, unelastic properties, deformation behavior, strength, and plasticity of ultrafine-grained titanium produced by equichannel angular pressing are discussed. Particlular emphasis has been placed on the grain-boundary unelasticity and the effects of external thermal and thermal-force actions on the deformation behavior and plastic deformation localization at the meso- and macroscale levels. The influence of cold plastic deformation of ultrafine-grained titanium on the grain-boundary unelasticity and temperature dependence of the mechanical properties is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 33–43, September, 2004.     

Spall fracture of coarse- and ultrafine-grained FCC metals under nanosecond high-current relativistic beam irradiation

Experimental data are presented on the fracture mechanism and plastic deformation and thickness of the spalled layer obtained on irradiation of targets made from coarse- and fine-grained fcc metals (copper and aluminum) by a nanosecond high-current relativistic beam. The general and special features inherent in the modification of the microstructure of the spalled layer and near the surface of the spall fracture are discussed for the coarse- and fine-grained materials of the targets. Possible reasons for the varying extent to which the characteristics of the spall fracture of the copper and aluminum targets are affected by the grain size are suggested. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 20–24, March, 2009.     

Influence of deviation from stoichiometry on the plasticity and mechanism of fracture of the boron-alloyed intermetallic compound Ni3Al obtained by self-propagating high-temperature synthesis

We have studied the effect that deviation of the composition of an ally from stoichiometry has on the plasticity , strength _B, and the fracture mechanism of the intermetallic compound Ni₃Al obtained by self-propagating high-temperature synthesis. The variation of the tensile strength, plasticity, type of fracture, and the cohesive strength _coh of grains have been show to be correlated. The cohesive strength increases with the Al content in the alloy, most rapidly up to 24.0 at. % Al.V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 104–110, April, 1994.     

Effect of chromium on structure,strength, and plasticity of high-temperature intermetallide Ni3Al

The effect of chromium on structure, strength characteristics, plasticity, and failure principles in the polycrystalline intermetallide Ni₃Al, produced by self-propagating high-temperature synthesis, is studied over the temperature range 290–1270 K. It is shown that the effect of chromium depends upon which element (nickel or aluminum) it is introduced in place of, although failure of alloys with various chromium contents at all deformation temperatures remains intercrystallite in nature.V. D. Kuznetsov Siberian Physicotechnical Institute at Tomsk State University. Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 30–36, June, 1993.