Structure and dynamics in levitated, liquid metal alloys

... first we levitate, then we melt, then we measure

After my PhD I joined the Institute for Material Physics in Space at the German Aerospace Center (DLR) in Cologne as a postdoc. There, I am currently investigating the relationship between the structure and dynamics of liquid metal alloys. Topicwise it is the exact opposite of what I did in my PhD. From thin soft matter polymer films, I am now dealing with bulk metal samples. From soft to hard, from interfaces to bulk materials... Consequently, that meant a lot of reading! 🤓
The image shows various scientific papers and notes, highlighting the effort it takes to dig into a new topic
The first half of a year as a postdoc was full of surprises. I was surprised that switching topics is so easily possible within academia, and that apparently, people had enough trust to offer me this position (or they didn't care too much).

And of course, there was and still is the constant excitement about the new field, the new techniques, and the new people around me. Switching topics was a gut decision, and to be honest, during the first months, I had ever-growing doubts if this was the right decision. Now, I know (at least I think I know) that it was the right decision. In a more and more specified academic system, I think it is necessary to also broaden and not only deepen your knowledge and expertise. 
And funnily enough, dealing with metals somehow brought along some great ideas about polymer science 😅 Sometimes, taking back a few steps isn't too bad after all...
My research is about the thermophysical and structural properties of metal melts and how they are correlated with each other. Thermophysical properties are for example the viscosity, density, surface tension, or specific heat capacity. I am interested in how the microscopic atomic structure influences these thermophysical properties. Even though my metal systems are molten, there is a certain short-range order present in these systems, i.e., the position of the atoms within their next or next-next neighbors is not random but somehow ordered. This order depends on the electronic configurations of the respective atoms. Alloy systems with a lot of different atomic species (multicomponent alloys) can become quite complicated to investigate, therefore, most of the research is done on pure, binary, or ternary metal systems. 
Basically, I am doing classical metallurgy. But there is one special thing about it. In order to measure, the thermophysical and structural properties as exact as possible, we are using a technique called levitation.

The metal sample, which typically is a few millimeters in size, is levitated either aerodynamically, or by means of an electromagnetic or electrostatic field (I will talk about that later). Subsequently, the levitated sample is molten (by lasers or by the electromagnetic field). The result is a levitating, molten metal sample and looks like this:
Four gray electrodes are surrounding a yellow/orange glowing and molten metal sample, which is levitating in an electrostatic field.
The photo is printed in: Brillo, Jürgen. Thermophysical Properties of Multicomponent Liquid Alloys, Berlin, Boston: De Gruyter Oldenbourg, 2016.
Fancy, right?! ☺️

Levitation has some advantages, the most important one is that you don't need any container, in which the metal sample is molten. Consequently, there aren't any interactions between the sample and the container wall, which could influence your measurements. Another advantage is that the sample is fully visible. That becomes important when you want to obtain the viscosity, density, or surface tension, which is usually done by measuring the size or movements/oscillations of the sample by means of a highspeed camera. Also, the background (or noise) is extremely low, which is very beneficial for scattering methods with x-rays and neutrons. 


Short disclaimer: 

This page is still under construction. Whenever I find the time, I will add the next chapter on metal physics and my postdoc journey. If you have specific questions, which are not answered somewhere here, please feel free to drop a message. 

Thanks ✌🏽
The image shows a meme of Patrick Star, who tries to build something out of wood, but apparently has no idea what he is doing. Somehow this meme feels like my first years as a phd student.

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