For the first time they observe how a metal is able to repair itself

For the first time they observe how a metal is able to repair itself

The fatigue in metals Implies Gradual failures through the incremental propagation of Cracks under repetitive mechanical load. In structural applications, it represents up to the 90% of failures. Its prevention is based on the implementation of large factors of Security & Design. In development metallurgical Traditional for fatigue resistance, microstructures are produced for stop or delay the progression of cracks. But its growth is supposed to be irreversible.

Scientists have recently witnessed for the first time pieces of metal that crack and then fuse together without human intervention, overturning fundamental scientific theories in the process. If the newly discovered phenomenon can be harnessed, it could usher in a engineering revolution, one in which engines, bridges and self-repairing aircraft could reverse the damage caused by wear and tear, making them more Safe and durable. The research team of Sandia National Laboratories and Texas A&M University described his findings in that regard in the journal Nature.

“It was absolutely Awesome to see it first hand Brad Boyce, a materials scientist at Sandia and one of the authors of the research, said Brad Boyce. What we have confirmed is that metals have their own capacity. Intrinsic and natural for Heal themselves, at least in the case of fatigue damage to nanoscale”. This deterioration is a way for machines to wear out and eventually break. Stress or repeated movement causes the formation of Microscopic cracks. Over time, these cracks grow and spread until a snap occurs and the entire device breaks.

The fissure that Boyce and his team saw disappear was one of these small but important fractures, measured in nanometers. “From the solder joints in our electronic devices to the engines in our vehicles and the bridges we drive over, these structures often fail unpredictably due to charging cyclical that leads to the onset of cracks and eventual fracture,” Boyce continued. When they fail, we have to deal with Replacement coststhe Wasted time and, in some cases, even with injury or loss of life. The economic impact of these failures is measured in hundreds of billions of dollars each year for the U.S. UU”.

Although specialists have created some self-healing materials, mostly plastics, the notion of a self-healing metal has largely been the domain of superhero movies. “The cracks in metals were only expected to get bigger, not smaller. Even some of the basic equations we use to describe crack growth exclude the possibility of such healing processes,” Boyce said.

In 2013, Michael Demkowicz, then an assistant professor in the department of materials science and engineering at the Massachusetts Institute of Technology (MIT), now full professor at Texas A&M, He began working on conventional materials theory. He published a new theory, based on findings in Computer simulations, which under certain conditions The metal should be able to weld the closed cracks formed by wear.

Experts at the Center for Integrated Nanotechnologies, a Department of Energy user facility jointly operated by Sandia and Los Alamos National Laboratories, inadvertently found that Demkowicz’s assessment was true.

“Certainly we weren’t looking for it.”Boyce said. Khalid Hattar, now an associate professor at the University of Tennessee, Knoxville, and Chris Barr, who works for the Office of Nuclear Energy of the Department of Energy, were conducting the experiment at Sandia when the discovery was made. They only intended to evaluate how it was formed.n the cracks and spread through a nanoscale piece of platinum using a specialized electron microscope technique they had developed to repeatedly pull on the ends of the metal 200 times per second.

Surprisingly, about 40 minutes after the experiment, the damage changed course. One end of the crack merged as if retracing his steps, leaving no trace of the previous injury.. Over time, it grew back in a different direction. Hattar called it an “unprecedented perception.” Boyce, who knew the theory, shared his findings with Demkowicz. “I was very happy to hear it, of course,” he said. The professor then recreated the experiment in a computer model, proving that the phenomenon witnessed at Sandia was the same one he had theorized years earlier.

Still Much is unknown about the self-healing process, including whether it will become a practical tool in a manufacturing environment. “It is likely that the extent to which these findings are generalizable becomes a topic of in-depth research,” Boyce said. We show that this happens in nanocrystalline metals in a vacuum. But we don’t know if this can also be induced in conventional metals in the air.” However, despite all the unknowns, the discovery remains A leap forward at the frontier of materials science. “I hope this step encourages materials researchers to consider that, under the right circumstances, they can do things we never expected,” Demkowicz concluded.


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