The recent experiments conducted at the U.S. government’s Sandia National Laboratories have demonstrated that pieces of pure platinum and copper can spontaneously heal cracks caused by metal fatigue. Metal fatigue occurs when metal is subjected to repeated stress or motion, leading to microscopic cracks that can worsen over time and potentially cause catastrophic failures in machines, vehicles, and structures, including aviation and infrastructure.
During the experiments, the researchers used a technique that applied stress to the tiny metal pieces at a high frequency, causing cracks to form and spread. However, after about 40 minutes, the metal pieces fused back together in a process the scientists referred to as “cold welding.” This healing phenomenon occurs at the nanoscale and involves the reforming of atomic bonds between relatively smooth and clean metal surfaces.
The researchers expressed optimism that this self-healing ability observed in platinum and copper could be engineered into other metals, including alloys like steel. The study’s findings may lead to the development of materials and engineering approaches that can mitigate fatigue-related failures in various structures. However, it’s important to note that this healing process occurs at the nanoscale and is not visible to the human eye.
While self-healing materials have been previously developed, mostly in the form of plastics, the possibility of self-healing in metals was predicted by one of the study’s co-authors, Michael Demkowicz, a decade ago. He believed that under certain conditions, metal under stress could exhibit the opposite effect and heal fatigue-related cracks.
Despite these promising results, practical applications of this self-healing ability in metals are still expected to take around another 10 years to develop. The researchers also noted that the observed healing occurred in a specific environment using an electron microscope, and they are uncertain if the process would happen in air or only in a vacuum. Nevertheless, even if it’s limited to vacuum environments, it could have significant implications for fatigue in space vehicles and subsurface cracks not exposed to the atmosphere.
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