See-Through Alloys Help NASA Understand Metal Making

Try to stare through a metal. Go ahead... I'll wait. Unless you're Superman, it simply can't be done. That's because metals are opaque, making it very difficult even for scientists to understand what exactly goes on when metals turn from a liquid into a solid. Now, with help from NASA, experts are running a series of experiments with special transparent alloys, allowing them to better understand how solidification occurs for the first time. 

So why is NASA involved? It should be mentioned that these experiments are going on aboard the International Space Station (ISS), as microgravity offers a unique lab environment where factors like Earth's gravitational pressure could be entirely avoided.

Traditional solidification involves crystallizing or "freezing" a liquid mixture of different atomic constituents. For example, a mixture of iron and carbon hardens into steel.

However, "the distribution of these constituents in the solid depends on the growth process and behavior at the interface between solid and liquid," principal investigator Nathalie Bergeon, of the Institut Matériaux Microélectronique Nanosciences de Provence in France, explained in a recent statement.

What Bergeon means by this is that, despite the fact that experts have long had the tools to observe the structure of metals before and after solidification, they were never able to observe the most important part, until now.

The alloys used in the experiment, called "plastic crystals," end with the same solid microstructures as metal. However, thanks to their uniquely transparent nature, experts were able to observe how they got there.

The experiments were also conducted with the ISS's Device for the study of Critical Liquids and Crystallization (DECLIC). This device facilitates and records each stage of the entire solidification process of alloys, allowing imagery to be sent to experts back on Earth without having to ship actual samples to and from the station.

The resulting observations were published in the journals Acta Materiala and the Physical Review Letters and could one day even help scientists craft new metal stronger and lighter than anything that currently exists.

Materials just in time for a second wind of space age-like aspirations to travel among the stars.

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