Scientists for the first time have witnessed pieces of metal crack, then fuse back together without any human intervention, overturning fundamental scientific theories in the process. If the newly discovered phenomenon can be harnessed, it could usher in an engineering revolution — one in which self-healing engines, bridges and airplanes could reverse damage caused by wear and tear, making them safer and longer-lasting. Fatigue damage is one form in which machines wear out and eventually break. Repeated stress or motion causes microscopic cracks to form. Over time, these cracks grow and spread until they snap, and the whole device fails. The researchers evaluated how cracks formed and spread through a nanoscale piece of platinum. They found that about 40 minutes into the experiment, the damage reversed course, as per a release. One end of the crack fused back together as if it was retracing its steps, leaving no trace of the former injury. Over time, the crack regrew along a different direction, the release says. A lot remains unknown about the self-healing process, including whether it will become a practical tool in a manufacturing setting.
