Abstract
The article presents original experimental data on surface tension of the melts Fe100 – x Mnx (x = 4 ... 13 wt. %). Surface tension and density of the melt was measured by the method of sessile drop at heating from the liquidus temperature up to 1780 °C and subsequent cooling of the sample in the atmosphere of high-purity helium. Temperature and concentration dependences of surface tension and density of Fe – Mn melts was constructed. Manganese is a surface-active substance in iron melt. The value of surface tension coefficient of Fe – Mn melts decreases while Mn content increases. Experimental data on the surface tension of Fe – Mn melts is consistent with the theoretical dependences (Pavlova-Popiel equation and the Shishkovsky equation). During the study of microheterogeneity of Fe – Mn melts, correlation between the values of kinematic viscosity, surface tension and density was determined. Dependence of the fluidity of Fe – Mn melts on their density in the cooling mode has a linear character which indicates the implementation of the Bachinsky law. Discrepancy of values of the ratio of melt viscosity to the surface tension coefficient was obtained from experimental data and was calculated by the empirical formula. According to the experimental data on viscosity and surface tension of Fe – Mn melts, the authors have evaluated the entropy change in volume of the melt and change of surface entropy of the melt, respectively. Surface entropy of the melt and entropy in the melt volume decreases in absolute value with increase of Mn content in it. According to the results of the work, it was concluded that there is no destruction of the microheterogeneous structure of Fe100 – x Mnx melts (x = 4 ... 13 wt. %) when heated up to 1780 °С.
Highlights
Surface tension and density of the melt was measured by the method of sessile drop at heating from the liquidus temperature up to 1780 °C and subsequent cooling of the sample in the atmosphere of high-purity helium
The value of surface tension coefficient of Fe – Mn melts decreases while Mn content increases
Experimental data on the surface tension of Fe – Mn melts is consistent with the theoretical dependences (Pavlova-Popiel equation and the Shishkovsky equation)
Summary
Сплавы Fe – Mn с содержанием марганца 4, 6, 8, 10 и 13 вес. % были получены в лабораторных условиях в защитной атмосфере высокочистого гелия при нагреве до температуры 1600 °С с последующим охлаждением со скоростью ~1 °С/с. Химичес кий состав образцов определен с помощью спектромет ра SPECTROMIDEX (SPECTRO Analytical Instruments GmbH, Germany). Поверхностное натяжение измеряли методом сидящей капли в режиме нагрева до 1780 °С и последующего охлаждения образца. Затем запускали гелий до давления ~105 Па. Образцы выдерживали в камере с инертной средой в течение 5 – 8 мин при температуре плавления, затем производили нагрев до 1780 °С с шагом 30 °С. Профиль исследуемой капли снимали цифровой фотокамерой с копированием изображения на компьютер, геометрические размеры профиля капли определяли с помощью программы анализа изображений SIAMS 700 с точностью 0,3 – 0,6 град. Погрешность определения значений поверхностного натяжения не превышала 7 %. Метод измерения поверхностного натяжения металлических расплавов (метод сидящей капли) и установка для его реализации описаны в работах [18 – 19]
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