First 3D X-ray views of magnesium alloys could revolutionize lightweight car design

Yahoo

5 hours ago

A breakthrough in materials science could help engineers design cars that are stronger, lighter, and more fuel-efficient.
University of Michigan researchers have used powerful X-rays to capture the first-ever 3D views of microscopic structures inside lightweight magnesium alloys, revealing how they absorb stress without breaking.
The discovery opens the door to wider adoption of magnesium in the automotive industry, potentially reducing costs and improving performance
Funded by the U.S. Department of Energy, the study offers fresh insight into how magnesium alloys react under mechanical stress.
Magnesium is 30% lighter than aluminum, and while some manufacturers already use it for non-load-bearing components, its broader use has been limited by its unpredictable behavior under strain.
Understanding and controlling that behavior could make magnesium a mainstream material for vehicle production.
Every metal's crystalline structure—the ordered, repeating arrangement of atoms—determines how it responds when pulled or bent.
Steel and aluminum have multiple 'slip systems' that let atoms shift easily in any direction, enabling them to stretch without fracturing. Magnesium is more restricted, able to slip atoms in only a few directions.
How magnesium handles stress
When pulled in directions that do not allow easy slipping, magnesium alloys form 'deformation twins.'
These are mirror-image regions in the crystal structure created when atoms in a certain area shift orientation. It is similar to folding a sheet of paper so that one side mirrors the other along the crease.
This twinning process increases ductility, allowing the material to stretch in more directions, but excessive twinning can create clusters of defects that eventually cause cracks.
In their experiments, the U-M team found that all three types of twins formed at 'triple junctions,' where three crystals meet, and that defects always appeared where the twin touched another crystal.
According to Ashley Bucsek, assistant professor of mechanical engineering and materials science, this consistent behavior could be key to optimizing magnesium's lifetime in demanding applications.
Before applying stress, the researchers scanned the sample with a small-scale CT machine to map crystal grain orientation. They then selected a grain ideally positioned for tracking the twinning process.
X-ray imaging in action
To capture the changes in unprecedented detail, the team used the European Synchrotron Radiation Facility in France. Its high-powered X-rays allowed the scientists to image the chosen grain without damaging the sample.
They used a technique called dark-field X-ray microscopy, which filters and magnifies X-rays diffracted at specific angles associated with the target grain.
The sample was stretched under three different loads—0.6, 30, and 45 megapascals—typical of forces in automotive parts.
Between each load, the researchers imaged the grain, effectively watching the twin form and evolve in real space.
Lead author Sangwon Lee, a U-M doctoral student, described the experience as 'a front-row seat' to twinning as it happened.
These high-resolution images are a first step toward tailoring magnesium alloys to be both more ductile and more stable, bringing them closer to large-scale use in cars and other vehicles. The researchers plan to capture these changes in real time during future experiments.
The study appears in the journal Science.
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