Cracked piece of metal 'heals itself' in world first
Scientists have discovered a piece of platinum that appears to 'heal' its cracks after metal fatigue
Researchers from Sandia National Laboratories and Texas A&M University set out to investigate the the resilience of platinum but instead, they observed something unexpected.
In a world-first study, Scientists tugged at a piece of metal which - after 40 minutes of observation - began to heal itself in one corner before doing so in another direction.
Using a 'specialised transmission electron microscope' technique, the scientists were able to 'tug' at each end of the metal. The piece of platinum - only measuring 40 nanometres in thickness - was suspended inside a vacuum during the process.
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The pulling rate of 200 times a second caused 'microscopic breaks' - or cracks - in the metal. This type of observation is called fatigue damage, and it happens when metals are weakened as a result of heavy loading or stress.
Science Alert explained that this type of wear-and-tear is what causes machines and structures to eventually break.
However, what surprising is that the metal began to close and 'heal' the cracks after about 40 minutes. Typically, a significant amount of heat is required to cause metals to change form, though this experiment was conducted at room temperature.
Scientist of Sandia National Laboratories, Brad Boyce, expressed his astonishment saying: 'This was absolutely stunning to watch first-hand.
'We certainly weren't looking for it. What we have confirmed is that metals have their own intrinsic, natural ability to heal themselves, at least in the case of fatigue damage at the nanoscale.'
The team published the results of this study in July earlier this year. Whilst study's results showcased the advances in understanding self-healing properties of some metals, scientists are still baffled as to the mechanisms behind it.
One potential explanation is the process of cold welding, where metal surfaces can come 'close enough together' to allow their atoms to entangle, causing a process that appears to heal cracks in the metal's surface.
With the metal being observed in a vacuum, no air particles or contaminant could interfere with the process, allowing the process to happen smoothly.
In saying that, the vacuum conditions means that there is still uncertainty as to whether the results can be replicated in a natural environment. The scientists do remain hopeful!
Texas A&M professor, Michael Demkowicz, described that the study supports his older theories about metal self-healing behaviour - at a nanoscale level - which he showcased in computer models.
He expanded: 'My hope is that this finding will encourage materials researchers to consider that, under the right circumstances, materials can do things we never expected.'