A delicious chocolate chip cookie all comes down to its bake. A minute too long and you'll be munching on a crunchy cookie. Seconds too soon, and you've got nothing but goo. The key to achieving the perfect cookie is watching it bake.
Andrew Chuang and Dileep Singh, researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory, teamed up with DOE's Pacific Northwest National Laboratory (PNNL) researchers to perfect a recipe of their own - not for cookies, but for aluminum alloys used in our vehicles, making them more energy efficient and less dependent on imported raw materials.
"Our main work was to design and then run the experiment, and that allowed us to monitor the structural changes in the alloys in real time," said Chuang, a physicist in the X-ray Science division of Argonne's Advanced Photon Source (APS).
They used the beamline at the APS, a DOE Office of Science user facility, to observe the solidification of the molten alloy while applying ultrasonification energy to the system. Ultrasonification uses sound waves at frequencies too high for humans to hear. As the ultrasound waves pass through the material, they transfer mechanical energy to it, producing a tougher, more ductile aluminum that performs better. This allows industry to use more recycled aluminum in future vehicles, ultimately reducing material costs and the need for newly produced raw materials. Additionally, they used X-rays to determine at what temperatures they should apply the ultrasound to the aluminum as it cools and solidifies.
"The idea is that if you can control the microstructure of these alloys, you can get better performance for the properties, and using ultrasonic energy is one way to do it," said Singh, department director for the Applied Materials division's Materials for Harsh Environments department and an Argonne Distinguished Fellow.
Just like blue-ribbon-winning bakers, these researchers have also been recognized for their efforts, having recently been awarded ASM International's Henry Marion Howe Medal.
The medal is awarded in memory of a distinguished teacher, metallurgist and consultant to honor the authors whose paper has been selected as the best of those published in Metallurgical and Materials Transactions. Their paper, "In-situ Synchrotron X-ray Diffraction of Ultrasonic Microstructural Refinement During Solidification in a Commercial Al-Si-Mg Alloy," did just that.
"In the old days, if you wanted to do this kind of casting microstructure research, you had to do the casting and then do some process and then examine the microstructure afterwards," Chuang explained. "Our work here opened a new pathway to monitor this in real time so that you get the feedback right away."
By scaling up this technique, researchers hope this will make better use of our domestic supply chain of recycled aluminum - something of which they're all extremely proud.
"I'm happy we got recognition for the role we played here and how it can help manufacturing," Chuang said. "This isn't academic research that's 30-40 years away from application. This can be immediately used to make light-metal alloys with more recycled aluminum into a high-quality material."
Henry Marion Howe Medalists are Argonne researchers Chuang, Singh and Jonova Thomas, a former postdoctoral appointee who now serves the Naval Nuclear Laboratory. PNNL collaborators are Mark Bowden, Katherine Rader, Aashish Rohatgi and Alan Schemer-Kohrn.
This project was funded by DOE's Transportation Technologies Office as part of the Lightweight Metals Core Program. This research was conducted at PNNL in collaboration with Argonne. This study used resources of the APS, operated for the DOE Office of Science by Argonne.
Em Jankauski is a communications coordinator for Argonne's Advanced Energy Technologies division. She covers advanced energy technologies topics and has previously written about advances in transportation research and materials science and engineering. She's worked as a writer since 2017.