Abstract

The explosive solidification of supercooled liquids is analyzed using heating and cooling thermograms of various substances. As proof of the phenomenon of explosive solidification, thermograms in the temperature–time coordinates are presented for tellurium, bismuth, water, and acetic acid. A schematic cooling curve is used to demonstrate the structural changes occurring in a liquid phase and the stages of solidification, namely, the formation of crystal nuclei, their coalescence, and subsequent isothermal solidification. Explosive solidification at the second stage is characterized by a rapid temperature rise from a supercooling region to the melting temperature at the rates exceeding the cooling rate (i.e., heat removal) by 2–3 orders of magnitude. An attempt is made to explain the phenomenon of explosive solidification in terms of the well-known postulates of the cluster-coalescence model of solidification and the theory of chain reactions. The calculations demonstrate that the critical nucleus sizes are comparable with the unit cell sizes of the corresponding crystal lattices and the nucleus formation energy is comparable with the intermolecular bond energies. Based on the calculations of the heat released during nucleus formation and the interfacial surface energy released during the coalescence of crystal nuclei, we advance a hypothesis that crystalline clusters and stable crystal nuclei can serve as the “building blocks” of crystal growth along with molecules. The energy released during the formation of nuclei and their coalescence is shown to be equivalent to electromagnetic radiation quanta and to generate new centers of solidification, multiplication, and coalescence of nuclei. The calculations demonstrate that the energy released during the coalescence of many nuclei is high enough to quickly heat a substance from the supercooling region to the melting temperature. By analogy with the well-known thermal explosion diagram, we plotted and analyzed a similar diagram for the time dependence of the heat release and the heat removal during explosive solidification. The critical values of the beginning of the explosive process and the cooling rate of a liquid phase are found. The final stage of equilibrium solidification after explosive solidification is estimated.

中文翻译：

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过冷液体爆炸凝固的聚结机理

摘要

使用各种物质的加热和冷却热谱图分析过冷液体的爆炸固化。作为爆炸固化现象的证据，我们提供了碲、铋、水和乙酸的温度-时间坐标中的热谱图。冷却曲线示意图用于演示液相中发生的结构变化和凝固阶段，即晶核的形成、它们的聚结和随后的等温凝固。第二阶段的爆炸凝固的特点是温度从过冷区域快速上升到熔化温度，其速度超过冷却速度（即除热）2-3 个数量级。试图根据凝固的簇聚结模型的众所周知的假设和链反应理论来解释爆炸凝固现象。计算表明，临界核尺寸与相应晶格的晶胞尺寸相当，并且核形成能与分子间键能相当。基于对晶核形成过程中释放的热量和晶核聚结过程中释放的界面表面能的计算，我们提出了一个假设，即晶簇和稳定的晶核可以作为晶体与分子一起生长的“构件”。在原子核形成及其聚结过程中释放的能量被证明相当于电磁辐射量子，并产生新的凝固、增殖和原子核聚结中心。计算表明，在许多原子核聚结过程中释放的能量足够高，可以将物质从过冷区域快速加热到熔化温度。通过与众所周知的热爆炸图类比，我们绘制并分析了爆炸凝固过程中放热和放热的时间依赖性的类似图。找到了爆炸过程开始和液相冷却速度的临界值。估计爆炸凝固后平衡凝固的最后阶段。