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<p>As a result of research using the boiling point method, the partial pressure of magnesium above Mg–Sn alloys was determined, represented by the temperature-concentration dependence. The decomposition of dimagnesium stannide into its constituent metals has been preliminarily established. The pressure of magnesium above the intermetallic compound (<i>p</i><sup><i>D</i></sup>) corresponds to the equation: ln <i>p</i><sup><i>D</i></sup> [Pa] = 26.695–21,250 × T<sup>−1</sup>. The decomposition temperature of Mg<sub>2</sub>Sn at atmospheric pressure corresponds to the value (1401 ± 131&#xa0;K), which, within the limits of determination errors, coincides with the boiling point of the melt (1494 ± 105&#xa0;K). The thermodynamic activities of magnesium and tin were determined, based on which the partial and integral mixing functions—entropy and enthalpy—were calculated and presented in tabular form. Based on the partial values of the vapor pressure of magnesium and tin, the boundaries of the vapor–liquid equilibrium fields at atmospheric pressure (101.3&#xa0;kPa) and in a vacuum (0.7&#xa0;kPa) were calculated. A complete phase diagram was constructed, including the boundaries of the liquid–vapor phase transition at the specified pressures. A pressure drop in the system below 0.7&#xa0;kPa may be accompanied by the crystallization of dimagnesium stannide from the melt. The boiling point of magnesium at atmospheric pressure is 1100&#xa0;°C, in a vacuum −&#xa0;695&#xa0;°C, tin –2609&#xa0;°C and 1791&#xa0;°C, respectively. The areas of coexistence of liquid and vapor are large in terms of temperature. The boiling point of the melt in a vacuum (821&#xa0;°C), corresponding to dimagnesium stannide, exceeds the melting point of the compound (770.5&#xa0;°C) by ⁓50&#xa0;°C. The composition of the equilibrium vapor phase is represented by magnesium in virtually the entire range of component concentrations. Thus, at a content of 0.1 wt. % Mg (1 × 10<sup>–3</sup> at. %) in the melt, the vapor phase will contain 99.73–99.76 wt. % magnesium, with the remainder being tin. That is, the separation of magnesium by distillation in a vacuum does not present any technological difficulties.</p>

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Phase transition of melt-vapor in the magnesium–tin system and its technological application

  • 期刊论文

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  • 发表日期：

    2026年4月24日

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  • Valeriy Volodin,
  • Sergey Trebukhov,
  • Xeniya Linnik,
  • Arailym Mukangaliyeva,
  • Tatyana Chepushtanova,
  • Alina Nitsenko,
  • Nurila Burabayeva

摘要

As a result of research using the boiling point method, the partial pressure of magnesium above Mg–Sn alloys was determined, represented by the temperature-concentration dependence. The decomposition of dimagnesium stannide into its constituent metals has been preliminarily established. The pressure of magnesium above the intermetallic compound (pD) corresponds to the equation: ln pD [Pa] = 26.695–21,250 × T−1. The decomposition temperature of Mg2Sn at atmospheric pressure corresponds to the value (1401 ± 131 K), which, within the limits of determination errors, coincides with the boiling point of the melt (1494 ± 105 K). The thermodynamic activities of magnesium and tin were determined, based on which the partial and integral mixing functions—entropy and enthalpy—were calculated and presented in tabular form. Based on the partial values of the vapor pressure of magnesium and tin, the boundaries of the vapor–liquid equilibrium fields at atmospheric pressure (101.3 kPa) and in a vacuum (0.7 kPa) were calculated. A complete phase diagram was constructed, including the boundaries of the liquid–vapor phase transition at the specified pressures. A pressure drop in the system below 0.7 kPa may be accompanied by the crystallization of dimagnesium stannide from the melt. The boiling point of magnesium at atmospheric pressure is 1100 °C, in a vacuum − 695 °C, tin –2609 °C and 1791 °C, respectively. The areas of coexistence of liquid and vapor are large in terms of temperature. The boiling point of the melt in a vacuum (821 °C), corresponding to dimagnesium stannide, exceeds the melting point of the compound (770.5 °C) by ⁓50 °C. The composition of the equilibrium vapor phase is represented by magnesium in virtually the entire range of component concentrations. Thus, at a content of 0.1 wt. % Mg (1 × 10–3 at. %) in the melt, the vapor phase will contain 99.73–99.76 wt. % magnesium, with the remainder being tin. That is, the separation of magnesium by distillation in a vacuum does not present any technological difficulties.