Abstract The article presents original experimental data on surface tension of the Fe 100 – x Mn x ( x = 4–13 wt %) melts. Surface tension and density of the melt were measured by the sessile drop method at heating from the liquidus temperature to 1780°C and subsequent sample cooling in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe–Mn melts were plotted. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe–Mn melts decreases as Mn content increases. Experimental data on the surface tension of Fe–Mn melts is consistent with the theoretical dependences (the Pavlov–Popel’ equation and the Shishkovsky equation). During the investigation of Fe–Mn melt microheterogenity, correlation between the values of kinematic viscosity, surface tension, and density is revealed. Fluidity dependence of Fe–Mn melts on their density in the cooling mode has a linear character which indicates satisfaction of the Bachinskii law. Discrepancy in the melt viscosity ratios to the surface tension coefficient obtained from the experimental data and from the empirical formula is discovered. Using the experimental data on viscosity and surface tension of Fe–Mn melts, the entropy change in the melt’s bulk and the change in the melt’s surface entropy, respectively, are studied. The surface entropy and the bulk entropy in the melt decrease in their absolute value with its increasing Mn content. From the study results, it is concluded that there is no destruction of the microheterogeneous structure of Fe 100 – x Mn x ( x = 4–13 wt %) melts when heated up to 1780°C.

中文翻译：

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Fe-Mn 熔体的表面张力和密度

摘要 本文提供了 Fe 100 – x Mn x ( x = 4–13 wt %) 熔体表面张力的原始实验数据。在从液相线温度加热到 1780°C 并随后在高纯氦气气氛中冷却样品时，通过座滴法测量熔体的表面张力和密度。绘制了表面张力和 Fe-Mn 熔体密度的温度和浓度依赖性。锰是铁熔体中的一种表面活性物质。Fe-Mn 熔体的表面张力系数值随着 Mn 含量的增加而降低。Fe-Mn 熔体表面张力的实验数据与理论依赖（Pavlov-Popel' 方程和 Shishkovsky 方程）一致。在研究 Fe-Mn 熔体微观不均匀性、运动粘度值之间的相关性、表面张力和密度被揭示。在冷却模式下，Fe-Mn 熔体的流动性对其密度的依赖性具有线性特征，表明满足 Bachinskii 定律。发现了熔体粘度比与从实验数据和经验公式获得的表面张力系数的差异。利用Fe-Mn熔体粘度和表面张力的实验数据，分别研究了熔体体积的熵变化和熔体表面熵的变化。熔体中的表面熵和体积熵的绝对值随着其 Mn 含量的增加而降低。从研究结果可以得出结论，当加热到 1780°C 时，Fe 100 – x Mn x (x = 4–13 wt %) 熔体的微非均质结构没有被破坏。在冷却模式下，Fe-Mn 熔体的流动性对其密度的依赖性具有线性特征，表明满足 Bachinskii 定律。发现了熔体粘度比与从实验数据和经验公式获得的表面张力系数的差异。利用Fe-Mn熔体粘度和表面张力的实验数据，分别研究了熔体体积的熵变化和熔体表面熵的变化。熔体中的表面熵和体积熵的绝对值随着其 Mn 含量的增加而降低。从研究结果可以得出结论，当加热到 1780°C 时，Fe 100 – x Mn x (x = 4–13 wt %) 熔体的微非均质结构没有被破坏。在冷却模式下，Fe-Mn 熔体的流动性对其密度的依赖性具有线性特征，表明满足 Bachinskii 定律。发现了熔体粘度比与从实验数据和经验公式获得的表面张力系数的差异。利用Fe-Mn熔体粘度和表面张力的实验数据，分别研究了熔体体积的熵变化和熔体表面熵的变化。熔体中的表面熵和体积熵的绝对值随着其 Mn 含量的增加而降低。从研究结果可以得出结论，当加热到 1780°C 时，Fe 100 – x Mn x (x = 4–13 wt %) 熔体的微非均质结构没有被破坏。