Ann Arbor Times

Researchers at the University of Michigan have used advanced X-ray technology to obtain the first three-dimensional images of how magnesium alloys form microscopic structures under stress. The findings, published in Science and funded by the U.S. Department of Energy, could help make magnesium alloys more suitable for use in automotive manufacturing.

Magnesium alloys are about 30% lighter than aluminum, which makes them attractive for building lighter vehicles that use less fuel. While some car manufacturers already use these alloys for nonload-bearing parts, their broader adoption depends on improving their performance under mechanical stress.

The study focused on how the crystalline structure of magnesium reacts when subjected to different forces. Unlike steel and aluminum, which can stretch easily in many directions due to their atomic arrangement, magnesium’s structure only allows it to deform along a few paths. When pulled in other directions, it forms “deformation twins”—mirror-image sections within its crystal lattice—that allow additional stretching but can also lead to defects if too many form.

“We were surprised to find all three twins formed in triple junctions, where three crystals touch, and defects always formed where the twin touches another crystal. This consistency can help us understand twin microstructures to optimize the material lifetime,” said Ashley Bucsek, assistant professor at the University of Michigan and corresponding author of the study.

To observe this process, researchers mapped out grain orientations inside a sample using a CT scanner before selecting a specific grain for further analysis. They then used dark-field X-ray microscopy at the European Synchrotron Radiation Facility in France—one of only a few facilities worldwide capable of producing sufficiently powerful X-rays—to image changes as they applied increasing amounts of tensile strength typical for car parts.

“Real-space X-ray images gave us a front-row seat to observe twinning as stress was applied. We literally watched the twin appear and evolve with our own eyes for the first time,” said Sangwon Lee, doctoral student at University of Michigan and lead author.

These high-resolution images represent an initial step toward optimizing ductility without sacrificing stability in magnesium alloys. The research team plans future experiments that will capture these structural changes as they happen over time.

The project included contributions from researchers at Los Alamos National Laboratory and the National Institute of Standards and Technology.