PNNL's Kate Rader and Aashish Rohatgi win 2026 ASM Howe Medal for aluminium manufacturing research

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Pacific Northwest National Laboratory (PNNL) materials scientists Aashish Rohatgi and Kate Rader have been awarded the 2026 ASM International Henry Marion Howe Medal for research that advances scientific understanding of aluminium manufacturing. The award recognises the best paper published in Metallurgical and Materials Transactions and marks the culmination of nearly a decade of work on how ultrasonic processing affects aluminium solidification.

The research began in 2017, when Rohatgi set out to answer a challenging question: what happens inside aluminium castings when ultrasound is applied during solidification? While earlier studies had compared materials before and after processing, the underlying mechanisms remained largely unknown.

Four years later, Rader joined PNNL as a postdoctoral researcher in Rohatgi's team and helped lead a first-of-its-kind study that revealed how ultrasonic processing influences aluminium solidification in real time. The work advances scientific understanding of metal processing while supporting PNNL's mission to develop reliable manufacturing technologies for the automotive industry.

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

From experiment to award-winning research

The team left ANL in 2022 with an enormous dataset containing thousands of measurements. Rader led the analysis effort, working with collaborators Andrew Chuang, Dileep Singh and Jonova Thomas from ANL, along with Mark Bowden and Alan Schemer-Kohrn from PNNL. By 2025, the manuscript was ready for peer review.

The 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 while offering practical guidance for industrial applications.

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Their 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 described it as "an excellent and well-written study that adds new knowledge and insights to the field."

Established in 1923, the Henry Marion Howe Award is ASM International's oldest award and recognises 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.

Beyond the recognition, the research supports ongoing efforts to increase the use of recycled aluminium in automotive applications, helping reduce costs and strengthen domestic supply chains. It also highlights PNNL's ability to combine advanced characterisation 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. The research used resources at the Advanced Photon Source, a Department of Energy Office of Science user facility at ANL.

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