Advanced Solidification Studies on Transparent Alloy Systems: A New European Solidification Insert for Material Science Glovebox on Board the International Space Station

Abstract

Investigations on solidifying transparent model alloys have served frequently to gain knowledge on physical phenomena occurring during solidification of metallic alloys. However, quantitative results were only possible to obtain in thin samples where convection can successfully be suppressed. Quantitative studies on three dimensional phenomena not being affected by natural convection are thus only possible under microgravity conditions. Therefore, the European Space Agency (ESA) is planning to launch a new insert for the Material Science Glovebox (MSG) on board of the International Space Station (ISS) for studies on solidification phenomena in thick samples. Four different classes of transparent model alloys will be used to address the following scientific topics: (i) Columnar to Equiaxed Transition in Solidification Processing, (ii)Novel Peritectic Structures and In-Situ Composites; (iii) Solidification along an Eutectic Path in Binary Alloys; and (iv) Solidification along an Eutectic Path in Ternary Alloys. Here, we give details on the scientific objectives and the operational features ESA's new solidification device will offer. Introduction:

Dynamic instabilities of rod-like eutectic growth patterns: A real-time study

“…It now seems possible, and would indeed be very interesting, to study this question, and, more generally, explore the dynamics of multidomain rodlike patterns, by phase-field simulations [18]. Future experimental studies should undertake to grow single-domain rodlike eutectic patterns using thicker samples and appropriate solidification rate programs [13,28,29]. [13,17].…”

Eutectic and peritectic solidification patterns

“…In experiments, composition variations along the front are often created by convection, so that lamellae, rods, and mixed morphologies can be simultaneously observed in the same sample [31,40]. It it worth mentioning that a well-controlled study of the lamella-to-rod transition might be possible in a microgravity environment, in which composition gradients in a liquid can be maintained over sufficiently long times because of the absence of natural convection [41].…”

Coexistence of rod-like and lamellar eutectic growth patterns

“…We present real-time observations of a lamellar-to-rod transition during directional solidification of a model transparent eutectic alloy, namely the succinonitrile-d,camphor (SCN-DC) eutectic alloy, which ordinarily forms rod-like eutectic microstructures [17,18]. In situ experiments -the first of their kind in a microgravity environment-were carried out with the TRANSPARENT ALLOYS (TA) apparatus of the European Space Agency (ESA) onboard the International Space Station (ISS) [19,20]. Microgravity in an orbiting facility provides a unique tool for achieving diffusion controlled crystal growth from the melt without convection, irrespective of thermal and/or solutal density gradients in the liquid [21,22].…”