T. F. Grigor’eva

Mechanochemical synthesis of metastable solid solutions: Phase composition and microstructure evolution

The formation of Cu-Sn, Cu-In, Ni-Sn, and Ni-In supersaturated solid solutions during mechanochemical synthesis was studied. It was found that, in the process of synthesis, intermetallic compounds were formed first. Electron-microscopic examination revealed the presence of stacking faults and microstrains nonuniformly distributed in the initial stages of mechanochemical synthesis. Further mechanical activation makes the microstrain distribution more uniform. The microstructure of the metastable solid solutions is well described by models taking into account the major types of structural imperfections—second-order microstrains and deformation stacking faults.

Study of the products of interaction between iron and gallium during mechanical activation

Mechanochemical interaction between iron and gallium has been investigated. The multistage character and the dynamics of mechanochemical formation of the gallium solid solution in iron have been established. X-ray diffraction, electron microscopy, and atomic force microscopy have been used for studying structural and morphological peculiarities of products formed at various stages of mechanical activation. Mössbauer spectroscopy has been used for the investigation of local variations in the nearest surroundings of iron atoms during phase transformations.

Producing Cu/ZrO2 composites by combining mechanical activation and self-propagating high-temperature synthesis

The possibility of producing Cu/ZrO2 composites by combining mechanical activation and self-propagating high-temperature synthesis (SHS) is studied using x-ray diffraction and electron microscopy. It is shown that Cu/ZrO2 composites are formed in SHS using CuO/Cu/Zr mechanocomposite as a precursor.

Obtainment of the Fe0.70−xCrxAl0.3/Al2O3 nanocomposite by the method of SHS of mechanoactivated Cr2O3 + Fe + Al mixtures

Applying Mössbauer spectroscopy methods, we have studied the structure of nanocomposites obtained by a technique combining the preliminary mechanical activation of an 8.1 wt % Cr2O3 + 65.9 wt % Fe + 25 wt % Al mixture and self-propagating high-temperature synthesis (SHS). It has been found that, at the stage of mechanical activation, an Fe/Al/Cr2O3 composite with a low impurity of the Fe2Al5 intermetallide is formed. At the stage of SHS, the interaction between activated components of the mixture leads to the formation of the Fe0.7 − xCrxAl0.3 (x = 0 − 0.2)/Al2O3 composite.

Mechanochemical preparation of polymeric composites consisting of polyamide and clay materials

The mechanism of mechanochemical formation of composites consisting of PA-6 polyamide and clay minerals (pyrophyllite, kaolinite) was studied by IR spectroscopy and X-ray diffraction analysis. Composites with chemical bonding between the components are formed by activation of polyamide-pyrophyllite mixtures at polymer content c ≤ 10% and of polyamide-kaolinite mixtures at c ≤ 5%. Increased polymer content of the starting mixture “inhibits” the disordering of the silicate structure in the course of activation. Modification of polymers with mechanochemically formed polyamide/clay mineral composites improves the physicomechanical characteristics of the composite materials obtained.

Obtaining composites Cu/TiO2 by combining mechanical activation and self-propagating high temperature synthesis

The possibility of obtaining nanostructured composites Cu/TiO2 by combining mechanical activation and self-propagating high temperature synthesis was investigated by X-ray diffraction and electron microscopy.

Properties of metallic cements formed upon the interaction of mechanochemically synthesized copper alloys with liquid gallium and its eutectics: Interaction of Cu/Bi composites with liquid gallium

Atomic force microscopy and scanning electron microscopy were used to study the structure of metallic cements that are formed upon the interaction of Cu/Bi mechanocomposites with liquid gallium at room temperature. It has been established that the intermetallic compound CuGa2, which is the basic component of this metallic cement, is formed as tetragonal crystals 1–4 μm in size with a characteristic layeredspiral growth. The second phase—bismuth—is adsorbed at the growth steps in the form of disperse formations 70–250 nm in size; local bismuth accumulations of micron size are also observed. It is shown that in the metallic cement that is formed at room temperature regions of incompletely reacted Cu/Bi composite are retained.

Production of tungsten-based composite materials from mechanically activated powders

The effects of the composition and metal additives on the compressibility of mechanically activated tungsten-based powder mixtures, the volume changes upon sintering, and the structure and strength of high-temperature composite materials are studied.

How the tin concentration affects the interactions of intermetallic compounds of the Cu-Sn system with liquid gallium and a gallium-tin eutectic

Interactions in the copper-gallium-tin ternary system are studied. New phase formation involves the step of dissolution of solid copper alloys in a liquid phase. The induction period of tin segregation in an autonomous phase depends on tin concentration in the feed. The formation of solid solution of gallium in tin is suggested.

Study of the chemical interaction between mechanochemically synthesized Cu/Bi nanocomposites and liquid gallium

The phase composition and morphology of the diffusion-hardened compound containing Cu/Bi mechanocomposite with nanoscale metals and liquid gallium were examined by synchrotron radiation X-ray diffraction, as well as by atomic force and electron microscopic techniques.