Find out how hydrogen behaves in aluminum alloys

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Tensile properties and metallographic fractography of aluminum-based alloys containing zinc, magnesium and copper after aging at 120 ° C for 24 hours. a) Engineering stress-strain curves for uncharged and hydrogenated samples. b and c) Electron imaging of grain boundary cracks in hydrogen-charged alloys that have undergone tensile fracture. GB: grain boundaries; GBP: grain boundary precipitates. credit: Nature

Aluminum and its alloys are widely used in vehicles such as construction, home appliances, automobiles, ships, trains and airplanes due to their low density, high strength and abundance. However, aluminum alloys are prone to hydrogen embrittlement and, if not noticed early enough, can cause catastrophic failure during use. The effects of hydrogen in aluminum compared to steel are not well understood. Dr. Huan Zhao, a postdoctoral fellow at Max-Planck-Institut für Eisenforschung (MPIE), and her colleagues analyzed how hydrogen embrittles aluminum alloys and found the first approach to prevent this effect.Scientists are now publishing the latest results in their journals Nature..

“Hydrogen is the smallest of all elements and has the lowest solubility in aluminum, making it very difficult to detect on an atomic scale. Whether hydrogen enters aluminum and how much hydrogen enters aluminum. Where is it inside the microstructure and how does it affect its properties? All of these have been unresolved issues so far, “explains Zhao. MPIE researchers used so-called 7xxx aluminum, a high-strength aluminum class that is the primary material of choice for aircraft structural parts. They filled the sample with hydrogen and performed tensile tests, showing that ductility decreases as the amount of hydrogen increases.

The fracture surface showed that the cracks propagated especially along the grain boundaries. Through cryotransfer atom probe tomography, scientists have revealed that hydrogen is concentrated along their grain boundaries. “Our experiments have shown that the amount of hydrogen in the particles in the bulk is much higher than at the grain boundaries, but hydrogen embrittles the material only at the grain boundaries. Help with computational simulation. I was able to confirm it by borrowing. Hydrogen is attracted to the high energy region along the grain boundaries, causing material destruction, and the particles in the bulk rather act as hydrogen traps, propagating cracks. It hinders, “said MPIE, co-author of a recent publication.

Intermetallic compound particles may be the first solution

MPIE researchers have been able to show where hydrogen is after it has invaded during the processing or use of the material. It is important to control the traps, as this cannot actually be prevented.They recommend different strategies to prevent Hydrogen embrittlementIn particular due to the use of intermetallic compound particles that can trap hydrogen in the bulk material. In addition, controlling magnesium levels at grain boundaries appears to be important. “Magnesium pairs with hydrogen at grain boundaries to increase embrittlement,” says Zhao. “At the same time, we need to manipulate the correct size and volume fraction of the particles in the bulk to trap hydrogen while maintaining the strength of the material.”

Further research on “perfect” particle distribution and elimination of magnesium decoration Grain boundaries Pursuing advanced design High strength, hydrogenResistant aluminum alloy.

“Aggregation Researcher” unravels the mystery of the effects of hydrogen on materials

For more information:
Huan Zhao et al, Hydrogen Trap and Embrittlement in High Strength Al Alloys, Nature (2022). DOI: 10.1038 / s41586-021-04343-z

Provided by
Max Planck Society

Quote: Https: // How hydrogen works in an aluminum alloy obtained on February 17, 2022 (February 17, 2022) Find out what to do

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Find out how hydrogen behaves in aluminum alloys

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