A team of scientists have observed how a metal “heals” itself, something never seen before.
Many of us remember the 1991 movie “Terminator 2: Judgment Day”where an evil, time-traveling, shape-shifting android named T-1000 was made of a liquid metal with a unique quality: whether affected by explosions or bullets, his metal healed itself.
Is a self-healing metal only possible in science fiction? Apparently not.
Recently, a team of scientists from Sandia National Laboratories in New Mexico and Texas A&M University studying metal fatigue in platinum, a phenomenon in which microscopic cracks develop in metals under repeated stress, were stunned to witness something never seen before: a piece of metal that had cracks “healed” itself.
The unexpected event
Researchers led by Brad Boyce, have made nanoscale experiments study how cracks form and propagate in metal under stress.
Using a technique of electronic microscope A specialized technology they had developed, the scientists took tiny chunks of metal made of pure platinum and copper, extracting the material from each side at a staggering speed of 200 times per second. As expected, the cracks began to form and spread. However, around 40 minutes after the experiment, the pieces of metal merge spontaneously..
The green mark indicates where a crack formed and re-merged. The red arrows indicate the direction of the pulling force which unexpectedly triggered the phenomenon. Credit: Dan Thompson.
This process is known as cold welding. It’s all happening at the nanoscale, which means it’s not visible to the human eye. Cold welding occurs when two pieces of metal, whose surfaces must be smooth and clean, are joined together. form atomic bonds that facilitate self-repair. Essentially, it allows you to weld metal without heat. But now scientists have shown that this process can happen spontaneously without careful preparation, opening up a world of new applications.
Researcher Ryan Schoell, using a specialized transmission electron microscope technique to study nanoscale fatigue cracks. Credit: Craig Fritz.
The pieces of metal used in the experiments were about 40 nanometers thick and a few micrometers wide.
While healing has been observed in platinum and copper, simulations suggest that this phenomenon could also occur in other metals.
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While it’s not yet clear exactly how it happens or how it can be used, for scientists the event paves the way for innovative apps in the near future, as this ability would allow engineering metals to create self-repairing machines and structures in the relatively near future. Imagine bridges, planes, land vehicles, or any mechanical part subject to wear and tear that can “repair” itself.
The results were published in the journal Nature.
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