“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, who helped lead the study published in the journal Nature. The researchers called this healing “cold welding.” But about 40 minutes into the experiment, the metal fused back together. In the experiments at the US government’s Sandia National Laboratories in New Mexico, the researchers used a technique that pulled on the ends of the tiny metal pieces about 200 times per second. Metal fatigue can cause catastrophic failures in areas including aviation - jet engines, for instance - and infrastructure - bridges and other structures. Metal fatigue occurs when metal - including parts in machines, vehicles and structures - sustains microscopic cracks after being exposed to repeated stress or motion, damage that tends to worsen over time. They expressed optimism that this ability can be engineered into metals to create self-healing machines and structures in the relatively near future. Scientists on Wednesday described how pieces of pure platinum and copper spontaneously healed cracks caused by metal fatigue during nanoscale experiments that had been designed to study how such cracks form and spread in metal placed under stress. Photo: Dan Thompson/Sandia National Laboratories/Handout via Reuters Red arrows indicate the direction of the pulling force that unexpectedly triggered the phenomenon. Green marks the spot where a fissure formed, then fused back together in this artistic rendering of nanoscale self-healing in metal, discovered at the US government’s Sandia National Laboratories, in this undated handout image.
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