Kate Rader and Aashish Rohatgi Lead Award-Winning Research Advancing Aluminum Manufacturing

In 2017, Pacific Northwest National Laboratory (PNNL) materials scientist Aashish Rohatgi set out to answer a difficult question: What happens inside aluminum castings when ultrasound is applied during solidification? Previous studies could only compare materials before and after processing, leaving the underlying mechanisms largely unknown.

Four years later, materials scientist Kate Rader joined the Laboratory as a postdoc in Rohatgi’s team and helped lead a first-of-its-kind study that revealed how ultrasonic processing influences aluminum solidification in real time. Their work has earned the 2026 ASM International Henry Marion Howe Medal, awarded annually for the best paper published in Metallurgical and Materials Transactions.

The research advances scientific understanding of metal processing while supporting PNNL’s mission to develop reliable manufacturing technologies for the automotive industry.

“Receiving this award feels validating because this was many years of work and effort,” Rader said. “It was almost a year of just planning the experiments, then a couple years of analyzing the data afterwards. Having that extra visibility is exciting and will hopefully lead to more partnerships moving forward.”

Working with collaborators at Argonne National Laboratory (ANL), they secured highly competitive beamline access at the Advanced Photon Source and developed specialized experimental hardware and procedures. Rader played a key role in planning and executing the experiments, collecting data during four days of synchrotron beamtime and managing the significant logistic and technical challenges associated with a novel in situ study.

“Not everything goes exactly as planned, and these were some very difficult experiments,” said Rohatgi. “Nobody had ultrasound applied to molten metal while it was solidifying, so that was the uniqueness of our experiments.”

The team left ANL in 2022 with an enormous dataset containing thousands of measurements. Rader led the analysis effort, working with collaborators across institutions to transform complex data into new scientific insights. They collaborated with Andrew Chuang, Dileep Singh, and Jonova Thomas from ANL and with Mark Bowden and Alan Schemer-Kohrn from PNNL. By 2025, the manuscript was ready for submission for peer review.

“I had never done anything like this before, so I had to rely on other experts to point me in the right direction,” said Rader. “It’s one of the first things at PNNL that I was able to see through from start to finish. I never would have been able to do this without their support and encouragement.”

The resulting study provided one of the first real-time views of ultrasonic processing during metal solidification, helping researchers identify how and when ultrasound influences microstructural development. The findings establish a stronger scientific foundation for future ultrasonication-assisted manufacturing processes and offer practical guidance for industrial applications.

Rader and Rohatgi’s paper, “In-Situ Synchrotron X-Ray Diffraction of Ultrasonic Microstructural Refinement During Solidification in a Commercial Al-Si-Mg Alloy,” was first selected as an Editor’s Choice article, placing it among the journal’s most notable publications. Reviewers praised it as “an excellent and well-written study that adds new knowledge and insights to the field.”

“I feel this paper really demonstrates some of the great collaborations we can do here at PNNL with people across the Lab and our fellow national labs,” said Rader. “It’s also a great demonstration of how PNNL can do very applied research and great advanced characterization work that gives us new scientific insight that is going to be useful for our industry colleagues.”

The Henry Marion Howe Award, established in 1923, is ASM International’s oldest award and recognizes the best paper published in a given volume of Metallurgical and Materials Transactions. Rader and Rohatgi’s paper will be highlighted at the IMAT 2026 conference in Quebec City, Canada, in September.

“When Kate was hired, she had never done casting before, but she learned, understood, and now she does the ultrasound experiments on her own,” said Rohatgi. “It’s great to be recognized that we can produce such high-quality work at PNNL. We did these experiments and we published a fantastic paper that got the award, so it was almost nine years’ worth of validation. We all bring our strengths to the table, and it becomes a nice team effort.”

Beyond the recognition, the research supports ongoing efforts to increase the use of recycled aluminum in automotive applications, helping reduce costs and strengthen domestic supply chains. It also highlights PNNL’s ability to combine advanced characterization techniques with applied research to address industry challenges and accelerate the development of emerging technologies.

The work was funded by the Transportation Technologies Office within the Department of Energy’s Office of Critical Minerals and Energy Innovation, through the Light Metals Core Program. This research used resources at the Advanced Photon Source, a Department of Energy Office of Science user facility at ANL.