Similarly, the range of possible metals that can self-repair is also unknown. NASA launches robotic archaeologist Lucy on ambitious mission to Trojan asteroids Meet the robot keeping an eye on emperor penguins in Antarctica This sideways-scooting robot crab is so tiny, it fits through the eye of a needle This means they don't yet know if the process works only in a vacuum or not. Firstly, to observe the cold welding processes, scientists isolated the metals within a vacuum so that no atmospheric atoms interfered with the equipment. How widely implementable the researchers' new observations are remains unknown. This process does not appear to happen all the time, but only in cases where the local conditions induce crack flank contact." "When they contact, the two flanks heal back together in a process that metallurgists refer to as 'cold welding'. "In a nutshell, at the nanoscale, the local conditions around the crack tip are such that the two crack flanks are compressed into one another," Boyce said. But then, after 40 minutes, the metals fused themselves back together, leaving no trace of the cracks.Īccording to Boyce, the explanation for this miraculous self-repair lies in a process called "cold welding." In two of the metals, copper and platinum, cracks appeared and grew throughout the materials. The device applied an extremely small force - equivalent to the stomping of a mosquito's leg - in the form of 200 tiny tugs to the metals every second. In the new study, published July 19 in the journal Nature, scientists investigated how nano-size metal pieces respond to repeated stress using a device called a transmission electron microscope. In 2013, a team of researchers used computer models to show that metals may also be capable of performing the healing trick, but they were not able to study metals at the tiny scales necessary so couldn't get any real-world evidence. Metals sustain fatigue damage from repeated stress or motion, creating growing webs of microscopic cracks that can lead to catastrophic failures of jet engines, bridges and other vital structures.īut not all materials break under repeated strain: Some modern polymers and even ancient Roman concrete have been shown to repair their microcracks over time.
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