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Research paper thumbnail of Physical problems in crystal growth by the Stepanov method

Journal of Crystal Growth, 1980

The paper deals with main directions of the development of the Stepanov method. Crystals of prede... more The paper deals with main directions of the development of the Stepanov method. Crystals of predetermined geometry and shape are obtained by application of the capillary shaper method. It is also of importance to optimize the structural perfection of the shaped crystals. Special studies have been carried out on the determination and control of the thermo-elastic stresses involved in the growth of shaped crystals from the melt.

Research paper thumbnail of Growth and properties of shaped crystals

Journal of Crystal Growth, 1987

The paper summarizes the results of some shaped crystal growth research being carried out at the ... more The paper summarizes the results of some shaped crystal growth research being carried out at the Ioffe Physico-Technical Institute in Leningrad and at some other institutions in the USSR, which were presented at the Stepanov Conference in Leningrad in 1985. The properties of shaped crystals and new versions of the Stepanov method are discussed.

Research paper thumbnail of Study of plastic properties of laminated LiF monocrystals

Fizika tverdogo tela, 1980

Research paper thumbnail of Dislocation absorption of ultrasound in the lamellar eutectic composition Al-Al 2 Cu

Physics of the Solid State, Mar 1, 1996

Research paper thumbnail of Internal Friction in the Superconducting Ceramic (Bipb) 2 SR 2 Ca 2 Cu 3 O y in the 6-290 K Temperature Range

Research paper thumbnail of Inhomogeneity of Bi-containing HTSC material obtained by melting

Physics of the Solid State, Nov 1, 1996

Research paper thumbnail of Wear and Coefficient of Friction of a Supermodified Hypereutectic Aluminum–Silicon Alloy

Research paper thumbnail of Comparative Analysis of Crystal Growth on Earth and on a Space Station for CrSi2 Synthesized from Zn Melt in the Cr–Si–Zn System

Technical Physics, 2020

We have analyzed crystal growth in "terrestrial" conditions and in conditions on a space station.... more We have analyzed crystal growth in "terrestrial" conditions and in conditions on a space station. It is shown that CrSi 2 crystals grown from the Zn melt of the Cr-Si-Zn system in zero-gravity conditions exhibit an excess stress comparable with the excess pressure in the melt due to the support reaction on Earth, as well as the Laplace pressure.

Research paper thumbnail of Structural and Mechanical Properties of Directionally Solidified Al-Si Alloys

Journal of Materials Engineering and Performance, 2019

This review covers research aimed at finding the optimum composition and growth rate to obtain a ... more This review covers research aimed at finding the optimum composition and growth rate to obtain a highly modified Al-Si alloy using directional solidification. Investigations of microstructure and mechanical properties as a function of Si content and growth rate are analyzed. These works show that the composition yielding a eutectic microstructure changes considerably with increasing solidification rate in the range of 10 2-10 4 lm/s. The increase in ultimate tensile strength with increasing Si content up to that giving a completely eutectic microstructure is explained by a redistribution of volume content of a-Al and eutectic. The increase in tensile strength with increasing rate is explained by a decrease in microstructural scale accompanying the transformation of flake-to-fiber eutectic microstructure. The optimal fine fiber structure without any primary crystals of Al-Si alloy at a given Si content is obtained at the solidification rate giving a completely eutectic microstructure at that composition. Hypereutectic alloys can be fully modified using rapid cooling at such solidification rate that causes coupled growth of the eutectic for given composition of the alloy. Additional Sr modification results in a super-modified structure, high tensile strength and record high elongation.

Research paper thumbnail of Inelasticity and Nanostructured Dislocation Deformation of Aluminum–Silicon Alloy with a Supermodified Eutectic Structure

Technical Physics, 2019

Young's modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well ... more Young's modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.

Research paper thumbnail of The preparation of single crystals of the rare earth borides by the solution method and a study of their properties

Journal of the Less Common Metals, 1979

Single crystals of LaB,, SmBs, SmB,, EuB, and YbB, were prepared by crystallization from solution... more Single crystals of LaB,, SmBs, SmB,, EuB, and YbB, were prepared by crystallization from solutions in molten aluminium. Their compositions, lattice parameters, microhardnesses and etch pit densities were determined. Single crystals of LaBs prepared by the solution method were shown to be more perfect than zone-melted crystals. For EuB, and LaBs single crystals the dependence of the specific electrical resistance on hydrostatic pressure (up to 15 kbar) was measured. The electrical resistance of EuB, was observed to decrease markedly with an increase in the pressure; this may be due to an increase in the number of Eu3+ ions. A comparison of the electrical and galvanomagnetic properties of EuBs single crystals (prepared both by the solution method and by the floating-zone technique) with the electrical and galvanomagnetic properties of polycrystalline samples was made. The discrepancy between these properties is assumed to arise from the different number of Eu3* ions which is dependent on the preparation method.

Research paper thumbnail of ChemInform Abstract: Variation in the Electrical Properties of Single Crystals of Rare Earth(RE)Hexaborides with Temperature and Pressure

Chemischer Informationsdienst, 1982

Research paper thumbnail of The force law for dislocation–point defect interaction and dislocation kinetics studies by acoustic techniques

Acta Crystallographica Section A Foundations of Crystallography, 1981

Research paper thumbnail of Influence of Gravity on the Habit of Single Crystals of Compounds Grown from Solutions

Centrifugal Materials Processing, 1997

The effect of different gravity levels on the growth habit of single crystals of some compounds h... more The effect of different gravity levels on the growth habit of single crystals of some compounds has been determined. Isometric crystals were obtained both at microgravity and at 10–11g. Accelerations of 2–6g promoted the formation of elongated and flattened crystals. The microhardness of KCl and KBr crystals increased with increasing acceleration at which they were obtained).

Research paper thumbnail of Inelasticity and precipitation of germanium from a solid solution in Al-Ge binary alloys

Physics of the Solid State, 2015

The influence of precipitation of germanium atoms in a solid solution on the dependence of the in... more The influence of precipitation of germanium atoms in a solid solution on the dependence of the inelasticity characteristics on the germanium content in aluminum-germanium alloys prepared by direc tional crystallization has been studied. It has been shown that the Young's modulus defect, the amplitude dependent decrement, and the microplastic flow stress at a specified cyclic strain amplitude have extreme val ues at the eutectic germanium content in the alloy. The eutectic composition of the alloy undergoes a ductilebrittle transition. It has been found that there is a correlation between the dependences of the Young's mod ulus defect, amplitude dependent decrement, microplastic flow stress, and specific entropy of the exother mal process of germanium precipitation on the germanium content in the hypoeutectic alloy. The concen tration dependences of the inelasticity characteristics and their changes after annealing have been explained by the change in the resistance to the motion of intragrain dislocations due to different structures of the Guinier-Preston zones formed during the precipitation of germanium atoms.

Research paper thumbnail of Elastic Properties and Binding Forces in Crystals with Diamond and Sphalerite Lattices

Research paper thumbnail of Temperature Dependence of CzBr and CzI Single Crystals Elastic Constants

Physics of the Solid State

ABSTRACT

Research paper thumbnail of Lanthanide and actinide tetra- and hexaboride single crystals: Preparation, form of growth, and microhardness anisotropy

Physics of the Solid State

The question of the simultaneous crystallization of Y, lanthanide, and actinide tetra- and hexabo... more The question of the simultaneous crystallization of Y, lanthanide, and actinide tetra- and hexaborides in the same experiment is studied for the first time. It is established that the following pairs of compounds crystallize simultaneously: YB4 and YB6, SmB4 and SmB6, GdB4 and GdB6, TbB4 and TbB6, YbB4 and YbB6, and ThB4 and ThB6. The forms of growth of these single crystals are described. The results of measuring of their reticular and polar microhardness anisotropy are presented.

Research paper thumbnail of Shape memory effect and linear actuators based on Cu-Al-Ni single crystals

Bulletin of the Russian Academy of Sciences: Physics, 2009

ABSTRACT Recovery stress generation under thermal cycling has been experimentally studied in clam... more ABSTRACT Recovery stress generation under thermal cycling has been experimentally studied in clamped shape memory Cu-Al-Ni single crystals up to 9% reversible strain. It is shown that such crystals are capable of repeated force generation upon heating up to 600 K and single actuation when heated to 700 K with a maximal stress of 350 MPa. The main principles of designing cyclic linear actuators are considered and a technique for calculating their force characteristics is proposed. The calculation is based on the mathematical model of linear actuator.

Research paper thumbnail of Elasticity, anelasticity, and microplasticity of directionally crystallized aluminum-germanium alloys

Physics of the Solid State, 2014

The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have be... more The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have been studied under conditions of longitudinal elastic vibrations with a strain amplitude in the range of 10-6-3 × 10 ⎯4 at frequencies about 100 kHz. The ribbon shaped samples of the alloys with the germanium content from 35 to 64 wt % have been produced by drawing from the melt by the Stepanov method at a rate of 0.1 mm/s. It has been shown that the dependences of the Young's modulus defect, logarithmic decrement, and vibration stress amplitude on the germanium content in the alloy at a constant strain amplitude have an extremum at 53 wt % Ge. This composition corresponds to the eutectic composition. The dependences of the Young's modulus defect, the decrement, and vibration stress amplitude at a constant microstrain amplitude have been explained by the vibrational displacements of dislocations, which depend on the alloy structure.

Research paper thumbnail of Physical problems in crystal growth by the Stepanov method

Journal of Crystal Growth, 1980

The paper deals with main directions of the development of the Stepanov method. Crystals of prede... more The paper deals with main directions of the development of the Stepanov method. Crystals of predetermined geometry and shape are obtained by application of the capillary shaper method. It is also of importance to optimize the structural perfection of the shaped crystals. Special studies have been carried out on the determination and control of the thermo-elastic stresses involved in the growth of shaped crystals from the melt.

Research paper thumbnail of Growth and properties of shaped crystals

Journal of Crystal Growth, 1987

The paper summarizes the results of some shaped crystal growth research being carried out at the ... more The paper summarizes the results of some shaped crystal growth research being carried out at the Ioffe Physico-Technical Institute in Leningrad and at some other institutions in the USSR, which were presented at the Stepanov Conference in Leningrad in 1985. The properties of shaped crystals and new versions of the Stepanov method are discussed.

Research paper thumbnail of Study of plastic properties of laminated LiF monocrystals

Fizika tverdogo tela, 1980

Research paper thumbnail of Dislocation absorption of ultrasound in the lamellar eutectic composition Al-Al 2 Cu

Physics of the Solid State, Mar 1, 1996

Research paper thumbnail of Internal Friction in the Superconducting Ceramic (Bipb) 2 SR 2 Ca 2 Cu 3 O y in the 6-290 K Temperature Range

Research paper thumbnail of Inhomogeneity of Bi-containing HTSC material obtained by melting

Physics of the Solid State, Nov 1, 1996

Research paper thumbnail of Wear and Coefficient of Friction of a Supermodified Hypereutectic Aluminum–Silicon Alloy

Research paper thumbnail of Comparative Analysis of Crystal Growth on Earth and on a Space Station for CrSi2 Synthesized from Zn Melt in the Cr–Si–Zn System

Technical Physics, 2020

We have analyzed crystal growth in "terrestrial" conditions and in conditions on a space station.... more We have analyzed crystal growth in "terrestrial" conditions and in conditions on a space station. It is shown that CrSi 2 crystals grown from the Zn melt of the Cr-Si-Zn system in zero-gravity conditions exhibit an excess stress comparable with the excess pressure in the melt due to the support reaction on Earth, as well as the Laplace pressure.

Research paper thumbnail of Structural and Mechanical Properties of Directionally Solidified Al-Si Alloys

Journal of Materials Engineering and Performance, 2019

This review covers research aimed at finding the optimum composition and growth rate to obtain a ... more This review covers research aimed at finding the optimum composition and growth rate to obtain a highly modified Al-Si alloy using directional solidification. Investigations of microstructure and mechanical properties as a function of Si content and growth rate are analyzed. These works show that the composition yielding a eutectic microstructure changes considerably with increasing solidification rate in the range of 10 2-10 4 lm/s. The increase in ultimate tensile strength with increasing Si content up to that giving a completely eutectic microstructure is explained by a redistribution of volume content of a-Al and eutectic. The increase in tensile strength with increasing rate is explained by a decrease in microstructural scale accompanying the transformation of flake-to-fiber eutectic microstructure. The optimal fine fiber structure without any primary crystals of Al-Si alloy at a given Si content is obtained at the solidification rate giving a completely eutectic microstructure at that composition. Hypereutectic alloys can be fully modified using rapid cooling at such solidification rate that causes coupled growth of the eutectic for given composition of the alloy. Additional Sr modification results in a super-modified structure, high tensile strength and record high elongation.

Research paper thumbnail of Inelasticity and Nanostructured Dislocation Deformation of Aluminum–Silicon Alloy with a Supermodified Eutectic Structure

Technical Physics, 2019

Young's modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well ... more Young's modulus and the logarithmic decrement of oscillations at a frequency of ~100 kHz as well as the subgrain size and residual stresses in the strontium modified alloy of aluminum with 15 wt % silicon have been studied. The alloy was obtained with a solidification rate of 1 mm/s at the shifted eutectic point. The dependence of inelastic dislocation deformation on the applied oscillating stress has been obtained and analyzed. The effect of strontium modification on the microstrain diagram can be accounted for by transformation of the lamellar fiber structure of eutectic silicon into a superfine fiber structure.

Research paper thumbnail of The preparation of single crystals of the rare earth borides by the solution method and a study of their properties

Journal of the Less Common Metals, 1979

Single crystals of LaB,, SmBs, SmB,, EuB, and YbB, were prepared by crystallization from solution... more Single crystals of LaB,, SmBs, SmB,, EuB, and YbB, were prepared by crystallization from solutions in molten aluminium. Their compositions, lattice parameters, microhardnesses and etch pit densities were determined. Single crystals of LaBs prepared by the solution method were shown to be more perfect than zone-melted crystals. For EuB, and LaBs single crystals the dependence of the specific electrical resistance on hydrostatic pressure (up to 15 kbar) was measured. The electrical resistance of EuB, was observed to decrease markedly with an increase in the pressure; this may be due to an increase in the number of Eu3+ ions. A comparison of the electrical and galvanomagnetic properties of EuBs single crystals (prepared both by the solution method and by the floating-zone technique) with the electrical and galvanomagnetic properties of polycrystalline samples was made. The discrepancy between these properties is assumed to arise from the different number of Eu3* ions which is dependent on the preparation method.

Research paper thumbnail of ChemInform Abstract: Variation in the Electrical Properties of Single Crystals of Rare Earth(RE)Hexaborides with Temperature and Pressure

Chemischer Informationsdienst, 1982

Research paper thumbnail of The force law for dislocation–point defect interaction and dislocation kinetics studies by acoustic techniques

Acta Crystallographica Section A Foundations of Crystallography, 1981

Research paper thumbnail of Influence of Gravity on the Habit of Single Crystals of Compounds Grown from Solutions

Centrifugal Materials Processing, 1997

The effect of different gravity levels on the growth habit of single crystals of some compounds h... more The effect of different gravity levels on the growth habit of single crystals of some compounds has been determined. Isometric crystals were obtained both at microgravity and at 10–11g. Accelerations of 2–6g promoted the formation of elongated and flattened crystals. The microhardness of KCl and KBr crystals increased with increasing acceleration at which they were obtained).

Research paper thumbnail of Inelasticity and precipitation of germanium from a solid solution in Al-Ge binary alloys

Physics of the Solid State, 2015

The influence of precipitation of germanium atoms in a solid solution on the dependence of the in... more The influence of precipitation of germanium atoms in a solid solution on the dependence of the inelasticity characteristics on the germanium content in aluminum-germanium alloys prepared by direc tional crystallization has been studied. It has been shown that the Young's modulus defect, the amplitude dependent decrement, and the microplastic flow stress at a specified cyclic strain amplitude have extreme val ues at the eutectic germanium content in the alloy. The eutectic composition of the alloy undergoes a ductilebrittle transition. It has been found that there is a correlation between the dependences of the Young's mod ulus defect, amplitude dependent decrement, microplastic flow stress, and specific entropy of the exother mal process of germanium precipitation on the germanium content in the hypoeutectic alloy. The concen tration dependences of the inelasticity characteristics and their changes after annealing have been explained by the change in the resistance to the motion of intragrain dislocations due to different structures of the Guinier-Preston zones formed during the precipitation of germanium atoms.

Research paper thumbnail of Elastic Properties and Binding Forces in Crystals with Diamond and Sphalerite Lattices

Research paper thumbnail of Temperature Dependence of CzBr and CzI Single Crystals Elastic Constants

Physics of the Solid State

ABSTRACT

Research paper thumbnail of Lanthanide and actinide tetra- and hexaboride single crystals: Preparation, form of growth, and microhardness anisotropy

Physics of the Solid State

The question of the simultaneous crystallization of Y, lanthanide, and actinide tetra- and hexabo... more The question of the simultaneous crystallization of Y, lanthanide, and actinide tetra- and hexaborides in the same experiment is studied for the first time. It is established that the following pairs of compounds crystallize simultaneously: YB4 and YB6, SmB4 and SmB6, GdB4 and GdB6, TbB4 and TbB6, YbB4 and YbB6, and ThB4 and ThB6. The forms of growth of these single crystals are described. The results of measuring of their reticular and polar microhardness anisotropy are presented.

Research paper thumbnail of Shape memory effect and linear actuators based on Cu-Al-Ni single crystals

Bulletin of the Russian Academy of Sciences: Physics, 2009

ABSTRACT Recovery stress generation under thermal cycling has been experimentally studied in clam... more ABSTRACT Recovery stress generation under thermal cycling has been experimentally studied in clamped shape memory Cu-Al-Ni single crystals up to 9% reversible strain. It is shown that such crystals are capable of repeated force generation upon heating up to 600 K and single actuation when heated to 700 K with a maximal stress of 350 MPa. The main principles of designing cyclic linear actuators are considered and a technique for calculating their force characteristics is proposed. The calculation is based on the mathematical model of linear actuator.

Research paper thumbnail of Elasticity, anelasticity, and microplasticity of directionally crystallized aluminum-germanium alloys

Physics of the Solid State, 2014

The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have be... more The structure, Young's modulus defect, and internal friction in aluminum-germanium alloys have been studied under conditions of longitudinal elastic vibrations with a strain amplitude in the range of 10-6-3 × 10 ⎯4 at frequencies about 100 kHz. The ribbon shaped samples of the alloys with the germanium content from 35 to 64 wt % have been produced by drawing from the melt by the Stepanov method at a rate of 0.1 mm/s. It has been shown that the dependences of the Young's modulus defect, logarithmic decrement, and vibration stress amplitude on the germanium content in the alloy at a constant strain amplitude have an extremum at 53 wt % Ge. This composition corresponds to the eutectic composition. The dependences of the Young's modulus defect, the decrement, and vibration stress amplitude at a constant microstrain amplitude have been explained by the vibrational displacements of dislocations, which depend on the alloy structure.