#EBSstories Improving magnesium alloys…despite jetlag

21-01-2021

A team from the United States is carrying out an experiment on ID06-HXM virtually, where they study magnesium alloys, used in the automobile industry, during heat treatment.

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It is early in the morning. Ashley Bucsek, Assistant Professor in Mechanical Engineering at the University of Michigan, in the US, is only just waking up but opens her laptop straight away from her bed: her experiment on magnesium alloys is in full swing at beamline ID06-HXM at the ESRF. Zoom has proven to be an exceptionally useful tool for the population in general, but for researchers doing an experiment, it is a “must”. On ID06-HXM they have a constant Zoom meeting running since the beginning of the experiment. “We can comment on how the experiment is developing live and all of us can see the screen of the control computer as the action takes place”, says Bucsek. “It also helps the fact that I was a visiting scientist a couple of years ago so I know all the team on the beamline – it makes communication very easy”.

This time, Bucsek and her team are studying high-strength, lightweight magnesium alloys, which have substantial potential for reducing the weight of automobiles and other transportation systems, and, as a consequence, improve fuel economy and reduce emissions.

However, compared to other structural metals, the development of commercial magnesium alloys and the understanding of these alloys’ physical metallurgy are less mature. “If we want to enable the widespread use of these alloys in industry, we need to improve their strength, fatigue resistance and formability”, explains Bucsek.

The crystallographic texture of magnesium alloys is very strong, with all the atomic arrangements pointing in a similar direction. This makes them strong in one direction but brittle in other directions. Heat treatments are used to make this texture less strong, which in turn makes the material properties the same in all directions and more machinable in general. This occurs due to a recrystallization process, where new crystals grow and the “old” crystals disappear.

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A screenshot of the Zoom session among the team while the experiment was taking place. Credits: A. Bucsek

Bucsek has gone (virtually) to ID06-HXM to apply heat treatments to some samples to discover what processes take place at the crystal level and what promotes changes in the structure. With the ID06-HXM team, they have used the technique of dark field X-ray microscopy, where they can see what is happening inside the material in situ, with a spatial resolution of 100 nanometres or better.

The new EBS has made the experiment much smoother: “Changes were immediately apparent: the brilliance is so strong that we don’t need to worry about the size of our sample, nor the time for collection, or the dynamic range of the detector, because we have more photons. This has been obvious from the very first image that we have seen”, says Bucsek.

Despite the peculiar circumstances, Bucsek asserts that the experiment has followed a classic pattern: “I don’t think this experiment in particular would be different if we were there. It is a classic story arc of things are going well, things are going better, then things are starting to go bad, then worse, and then you are in a hole and you can’t dig yourself out of it. When everything seems lost, you have a last-minute success. Heartbreak and triumph: same feelings, even remotely”, concludes Bucsek.

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Bucsek with the ID06 team during her stay at the ESRF in 2018. 

Text and video by Montserrat Capellas Espuny

Top image: Images from the mosaicity scans taken during the experiment. Credits: A. Bucsek.