Immortal robots on the horizon: metals have learned to “heal” cracks

The scenario from the sci-fi movie “Terminator” with fearless robots capable of self-healing can become a reality. Scientists observed how the metal “healed” its cracks without human intervention.

American researchers working at Sandia National Laboratories and Texas A&M University have disproved all existing ideas about metals by finding that wear cracks can heal on their own under certain conditions.

“It was amazing to see it live,” said Sandia scientist Brad Boyce, who led the study. “We confirmed that metals have an intrinsic, natural ability to heal themselves, at least in the event of fatigue damage at the nanoscale.”

The researchers note that such a discovery could revolutionize engineering and pave the way for self-healing engines, aircraft and even robots. Currently, the metals used to build critical infrastructure such as bridges and aircraft are subjected to multiple loads and movements that cause microscopic cracks to form over time.

“From the soldering of our electronics to the motors of the cars to the bridges we cross, all of these structures often fail unpredictably due to cyclic loading, leading to cracks and subsequent failure,” Boyce continues. “When they fail, we face replacement costs, lost time and, in some cases, even injury or death.”

Although much is still unknown about self-healing, scientists believe that so-called cold welding, which can occur at the tips of fatigue cracks in metals, could play a role in this process, allowing exposed metals to “join” under compression.

“Hopefully this discovery will encourage material researchers to consider that, under certain circumstances, materials can do things we don’t expect them to do,” said Michael Demkovich of the Massachusetts Institute of Technology, the author of a similar theory about self-healing metals proposed 10 years ago.