Saint-Petersburg Mining University, Saint Petersburg, Russia:

S. A. Savchenkov, Deputy Head of the Patent and Licensing Department, Leading Engineer of the Laboratory of Modern Technologies of Automated Production and Process Control Systems, e-mail: savchenkov_sa@pers.spmi.ru
V. Yu. Bazhin, Professor, Director of the D. I. Mendeleev Research Institute, Head of the Department of Automation of Technological Processes and Production, e-mail: bazhin_vyu@pers.spmi.ru
V. G. Povarov, Head of the Department of Scientific and Methodological Support of Research at the Core facilities Centre, e-mail: povarovvg@spmi.ru

The article is devoted to the research into the process of the triple magnesium-zinc-gadolinium master alloys synthesis. As a result of thermal analysis, the temperature intervals of thermal effects during the process of gadolinium recovery from its fluoride in the melt of KCl – NaCl – СaCl₂ salts with magnesium and zinc were established. As a consequence of a series of experiments, the main regularities of the magnesium-zinc-gadolinium master alloy synthesis from the selected technological salt mixture were recognized, and the main factors of the metallothermic process affecting the degree of gadolinium recovery were also determined. It is experimentally proved that during the triple Mg – Zn – Gd master alloy synthesis, the rational magnesium to zinc ratio, which reduces the synthesis temperature and synthesis time of triple master alloys when reducing gadolinium from the technological KCl – NaCl – СaCl₂ – GdF₃ salt mixture, is 1:2. The magnesium-thermal reduction process on zinc addition is characterized by the high extraction level of gadolinium (up to 99.2%). The microstructure analysis has showed that a uniform distribution of intermetallic compounds (Mg₃GdZn₆) in the magnesium-zinc double eutectic volume distinguishes the resulting 25Mg – 50Zn – 25Gd triple master alloys.

The authors express their gratitude to V. L. Ugolkov, Candidate of Technical Sciences, Senior Researcher of the Nanostructure Research Laboratory of the Institute of Silicate Chemistry of Russian Academy of Sciences, for assistance in conducting thermal analysis.

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