We review recent in situ solidification experiments using nonfaceted model transparent alloys in science-in-microgravity facilities onboard the International Space Station (ISS), namely the Transparent Alloys (TA) apparatus and the Directional Solidification Insert of the DEvice for the study of Critical Liquids and Crystallization (DECLIC-DSI). These directional-solidification devices use innovative optical videomicroscopy imaging techniques to observe the spatiotemporal dynamics of solidification patterns in real time in large samples. In contrast to laboratory conditions on ground, microgravity guarantees the absence or a reduction of convective motion in the liquid, thus ensuring a purely diffusion-controlled growth of the crystalline solid(s). This makes it possible to perform a direct theoretical analysis of the formation process of solidification microstructures with comparisons to quantitative numerical simulations. Important questions that concern multiphase growth patterns in eutectic and peritectic alloys on the one hand and single-phased, cellular and dendritic structures on the other hand have been addressed, and unprecedented results have been obtained. Complex self-organizing phenomena during steady-state and transient coupled growth in eutectics and peritectics, interfacial-anisotropy effects in cellular arrays, and promising insights into the columnar-to-equiaxed transition are highlighted.

我们回顾了最近在国际空间站（ISS）微重力科学设施中使用无面模型透明合金进行的原位凝固实验，即透明合金（TA）装置和用于研究临界液体的装置的定向凝固插入物和结晶（DECLIC-DSI）。这些定向凝固设备使用创新的光学视频显微镜成像技术来实时观察大样品中凝固图案的时空动态。与地面实验室条件相反，微重力保证液体中不存在或减少对流运动，从而确保结晶固体的纯粹扩散控制生长。这使得可以对凝固微观结构的形成过程进行直接的理论分析，并与定量数值模拟进行比较。一方面涉及共晶和包晶合金的多相生长模式，另一方面涉及单相、胞状和树枝状结构的重要问题已经得到解决，并获得了前所未有的结果。重点介绍了共晶和包晶稳态和瞬态耦合生长期间的复杂自组织现象、细胞阵列中的界面各向异性效应以及对柱状到等轴转变的有希望的见解。