Cracked Piece Of Metal Healed Itself In New Experiment, Scientists Stunned

A new experiment has left scientists stunned after a metal healed itself. Scientists from Sandia National Laboratories and Texas A&M University were testing the resilience of the metal, they were using a specialised transmission electron microscope technique to pull the ends of the metal 200 times every second, reported Science Alert.

A crack initially formed and spread. But about 40 minutes into the experiment, the metal fused back together.

The researchers called this healing “cold welding.”

The scientists observed that the metal was self-healing at ultra-small scales in a 40-nanometer-thick piece of platinum suspended in a vacuum. 

The groundbreaking discovery could revolutionise engineering. The findings of the experiment were published in the journal Nature.

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“This discovery could change engineering forever”- @PopSci

Self-healing machines may become reality, after scientists from Sandia and @TAMU recorded metal fusing without human intervention https://t.co/m0zAXIY1Jopic.twitter.com/j5kWJr6Xi4

— Sandia National Labs (@SandiaLabs) August 4, 2023

“The cold welding process is a metallurgical process that is known to occur when two relatively smooth and clean surfaces of metal are brought together to reform atomic bonds,” said Sandia National Laboratories materials scientist Brad Boyce. 

“Unlike the self-healing robots in the ‘Terminator’ movie, this process is not visible at the human scale. It occurs at the nanoscale, and we have yet to be able to control the process,” Mr Boyce added.

Metal pieces were about 40 nanometers thick and a few micrometres wide. While the healing was observed in the experiments only in platinum and copper, Boyce said simulations indicated that self-healing can occur in other metals and that it is “entirely plausible” that alloys like steel could exhibit this quality.

“It’s possible to envisage materials tailored to take advantage of this behavior,” Boyce said.

“Given this new knowledge, there may be alternative material design strategies or engineering approaches that could be devised to help mitigate fatigue failure. In addition, this new understanding may shed light on fatigue failure in existing structures – improving our ability to interpret and predict such failures,” Boyce added.

Scientists in the past have fashioned some self-healing materials, mostly plastics. Study co-author Michael Demkowicz, a Texas A&M University professor of materials science and engineering, predicted self-healing in metal a decade ago.

Demkowicz correctly figured that under certain conditions, putting metal under stress that ordinarily should worsen fatigue-related cracks could have the opposite effect.

“My guess now is that tangible applications of our findings will take another 10 years to develop,” Mr Demkowicz said.

“When I first made my predictions, some of the press said I was working on a T-1000. That’s still sci-fi,” Demkowicz said. “However, at the end of (TV series) ‘Battlestar Galactica,’ the crew adapted some Cylon (a fictional robot race) technology to help heal fatigue damage to their ship, making metal behave more like an organic tissue that can heal its own wounds. I’d say what we’re working on is more along the lines of the ‘Battlestar Galactica’ example.”

The self-healing was observed in a very specific environment using a device called an electron microscope.

“One of the big questions left open from the study is if the process also happens in the air, not just the vacuum environment of the microscope. But even if it only occurs in a vacuum, it still has important ramifications for fatigue in space vehicles, or fatigue associated with subsurface cracks that are not exposed to the atmosphere,” Mr Boyce said.