Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia:

S. N. Agafonov, Post-Graduate Student, e-mail: agafonovs@yandex.ru
S. A. Krasikov, Leading Researcher
L. B. Vedmid, Senior Researcher
S. V. Zhidovinova, Senior Researcher
A. A. Ponomarenko, Junior Researcher

Research of alumino-calciumthermal reduction of zirconium dioxide with obtaining of Al – Zr alloys, containing 50–60% of Zr, was carried out. Usage of methods of differential-thermal analysis (DTA) and X-ray diffraction analysis allowed to reveal that heating of charge materials of ZrO₂:Al and ZrO₂: (Al+Ca) with relationship of the components from 1.0:0.5 to 1.0:1.0 accompanied with transition to the kinetically active stage of interaction reaction after formation of liquid aluminum. The initial stage at alumino-thermal and alumino-calciumtermal reduction of ZrO₂ is characterized by formation of stable congruent Al₃Zr compound. Partial (15%) aluminum replacement by calcium in charge material promotes to decrease formation temperature of intermetallic compound from 1022 to 908 ^оС and to grow the size of exothermic effect corresponding to this process. Modeling of alumino-calciumtermal reduction of zirconium in the resistance furnace was coordinated with DTA data and characterized by good separation of metal and slag phases. Al₃Zr and Al₂Zr intermetallic compounds were recorded in obtained Zr – Al alloys, containing 50–55% of zirconium. Use of calcium as a reducing agent was accompanied by formation of Al4Ca compound in a metal phase. Application of controlled thermal conditions allowed to carry out the melting process on fusible final slags CaO – Al₂O₃ – CaF₂ and to achieve formation of alloys with oxygen concentration less than 0.15% and nitrogen concentration less than 0.01%, as well as extraction of more than 90% of zirconium into the metal. These observations testify the prospects of usage of such approach in the technology of metallothermal production of aluminum-zirconium alloys.

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