Mexico City.- Scientists have witnessed for the first time how pieces of metal cracked and then stuck together without human intervention, a discovery they called impressive because it could spark a revolution in engineering.
That metals can heal or repair themselves raises the possibility that in the future aircraft, engines and bridges may repair themselves to reverse damage caused by wear and tear, according to researchers at Sandia National Laboratory and Texas A&M University.
“It was absolutely impressive to see it firsthand. What we have confirmed is that metals have their own intrinsic and natural ability to heal themselves, at least in the case of fatigue damage at the nanoscale,” said materials scientist Brad Boyle.
One cause of machine wear and tear is fatigue damage. It occurs from repeated movement because it causes microscopic cracks to form. Eventually, they grow and spread until the entire device breaks down.
The crack that the researchers saw disappear was one of these (measured in nanometers). Although small, they are important because they cause machines to fail, and when they do, replacement costs, lost time and even personal injury or death must be dealt with, Boyce said in a statement.
Although scientists have been able to create self-repairing materials, most are plastic, so a metal capable of repairing itself was considered science fiction.
The Sandia National Laboratory noted that this finding overturns fundamental scientific theories. The results of the research published in “Nature” refer to a theory by Michael Demkowicz, a professor at Texas A & M University: in 2013 he theorized that under certain circumstances, metal should be able to weld cracks formed by wear.
The theory was confirmed while researchers Khalid Hattar and Chris Barr were evaluating how cracks were generated and spread at the nanoscale through a piece of platinum, although their intention was not to prove that theory.
They used a technique that allowed the ends of the metal to be pulled 200 times per second. To the surprise of the specialists, 40 minutes after the experiment, one end of the crack merged as if it were retracing its steps without leaving a trace of damage.
Many details about this self-healing process are still unknown. For example, if this phenomenon will be a useful tool in manufacturing environments. So far, it has been observed in certain metals under vacuum, but it is not known if it can occur in conventional metals exposed to air.
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