Browsing by Author "Gavrilov, Alexander I."

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    Formation of TiC-Cu nanocomposites by a reaction between Ti25Cu75 melt-spun alloy and carbon
    (Elsevier, 2018-10-02) Dudina, Dina V.; Korchagin, Michail A.; Gavrilov, Alexander I.; Bulina, Natalia V.; Batraev, Igor S.; Esikov, Maksim A.; Georgarakis, Konstantinos; Kato, Hidemi
    In this work, Ti25Cu75 melt-spun partially amorphous alloy was used as a source of Ti and Cu to synthesize in-situ TiC-Cu nanocomposites. The reaction between the alloy and carbon started during ball milling and continued during Spark Plasma Sintering. At the same time, during ball milling, the alloy experienced phase transformations: crystallization of the amorphous phase was followed by decomposition of TiCu3. Copper crystallites formed during the alloy transformations were the reason for the presence of copper regions 0.5–1 µm in size free from TiC nanoparticles in the sintered composites. The Ti-Cu intermetallics transformed into non-agglomerated TiC 10–20 nm in size distributed in the copper matrix. The hardness of the synthesized TiC-Cu nanocomposites exceeded that of composites obtained by conventional sintering of ball-milled Ti-C-Cu powders.
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    Towards a better understanding of the interaction of Fe66Cr10Nb5B19 metallic glass with aluminum: growth of intermetallics and formation of Kirkendall porosity during sintering
    (MDPI, 2023-01-15) Dudina, Dina V.; Kvashnin, Vyacheslav I.; Matvienko, Alexander A.; Sidelnikov, Anatoly A.; Gavrilov, Alexander I.; Ukhina, Arina V.; Moreira Jorge, Alberto; Georgarakis, Konstantinos
    Metallic-glass-reinforced metal matrix composites are a novel class of composite materials, in which particles of alloys with an amorphous structure play the role of reinforcement. During the fabrication of these composites, a crystalline metal is in contact with a multicomponent alloy of an amorphous structure. In the present work, the morphological features of the reaction products formed upon the interaction of Fe66Cr10Nb5B19 metallic glass particles with aluminum were studied. The composites were processed via spark plasma sintering (SPS), hot pressing or a combination of SPS and furnace annealing. The reaction products in composites with different concentrations of the metallic glass and different transformation degrees were examined. The products of the interaction of the Fe66Cr10Nb5B19 metallic glass with Al were observed as dense layers covering the residual alloy cores, needles of FeAl3 protruding from the dense shells as well as needles and platelets of FeAl3 distributed in the residual Al matrix. The possible role of the liquid phase in the structure formation of the reaction products is discussed. The formation of needle- and platelet-shaped particles presumably occurred via crystallization from the Al-Fe-based melt, which formed locally due to the occurrence of the exothermic reactions between aluminum and iron. At the same time, aluminum atoms diffused into the solid Fe-based alloy particles, forming an intermetallic layer, which could grow until the alloy was fully transformed. When aluminum melted throughout the volume of the composite during heating of the sample above 660 °C, a similar microstructure developed. In both Al–Fe66Cr10Nb5B19 and Al–Fe systems, upon the reactive transformation, pores persistently formed in locations occupied by aluminum owing to the occurrence of the Kirkendall effect.