8 ADVANCED MATERIALS & PROCESSES | MAY 2026 to high temperatures by adjusting its purity. “In space, micro-meteorites fly around and crash into things,” says Schuh. “If we want to keep them from destroying a satellite, for example, we might consider choosing a different purity metal than we would have otherwise. We could design reactive systems that sense when micro- meteorites are nearby and increase heat to make the satellite’s shell stronger. At these extreme conditions, purity could become a design parameter.” northwestern.edu. DESIGNING METAL FATIGUE RESISTANCE Scientists at the University of Illinois Urbana-Champaign demonstrated that fatigue resistance can be enhanced by controlling how metal plasticity localizes at small scales. This represents a new design strategy for engineering metallic alloys that are resistant to fatigue by leveraging unique deformation processes at the atomic scale. “Because this localization emerges from complex microstructural and deformation process interactions, it is difficult to predict where and how it will occur, making it challenging to account for during the engineering design stage,” says researcher JeanCharles Stinville. TESTING | CHARACTERIZATION MAKING METAL PURITY A DESIGN PARAMETER After bombarding both pure and alloyed metals with microscopic particles at ultra-high speeds across a range of temperatures, researchers at Northwestern University discovered that heat strengthens pure metals under extreme strain rates while alloys continue to soften. This surprising finding may enable engineers to tailor materials for extreme environments like hypersonic flight, space impacts, and advanced manufacturing. “One of the most basic tenets in metallurgy is that if you heat a metal, it becomes softer,” explains Northwestern’s Christopher Schuh, FASM, dean of the McCormick School of Engineering. “But we found that if you heat a pure metal and attempt to deform it at extremely high speeds, it flips. The opposite happens and the metal strengthens, resisting the deformation.” The team used a specialized technique that blasts hard, microscopic particles at speeds up to hundreds of meters per second. As a result, the tiny particles ballistically impact the metal, stretching it to 100 million percent of its original length in one second. The scientists performed the experiment with metal samples ranging from high purity to slightly alloyed versions of nickel, titanium, gold, and copper and from temperatures ranging from room temperature to 155°C. As temperatures increased, pure metals became stronger and harder. However, alloyed metals behaved typically, becoming softer when heated. The findings have implications for technologies that operate under intense heat and extreme strain rates. By heating a pure metal, it could be- come more resistant to sandblasting, ballistics, and hypersonic speeds. Engineers also could tune a metal’s response New findings challenge traditional assumptions of how metals behave when heated. Rolls-Royce completed specialized testing for the F130 engine in the U.S. Air Force B-52J Stratofortress. At the U.S. Air Force Arnold Engineering Development Complex, Tullahoma, Tenn., Rolls-Royce conducted altitude tests to demonstrate performance for long-duration, high-altitude missions and operability testing with distortion screens to replicate turbulent airflow and confirm engine stability under stress. rolls-royce.com. BRIEF Novel identified mechanisms of dynamic plastic delocalization in metal.
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