save those cracked engine blocks

[98valk]

https://charmingscience.com/a-cracked-piece-of-metal-healed-itself-in-an-experiment-that-stunned-scientists/


""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.

The research team from Sandia National Laboratories and Texas A&M University described their findings today in the journal Nature.

“This was absolutely stunning to watch first-hand,” said Sandia materials scientist Brad Boyce.

“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,” Boyce said.""

[Skinhead]

From the limited information in the article, and the drawings, it looks like the crack initiated along a grain boundary,  metal atoms arrange themselves in a crystalline matrix but due to mismatches and random orientation of the crystals, grains and boundaries form between the crystals.  Grain orientation can be somewhat controlled and the dislocations can be minimized with slow solidification and time at elevated temps, but it's an expensive process, and is normally used to manufacture things like turbine blades. 

In the article, they also state this was observed in a vacuum, which is required for a scanning election microscope.  Vacuum chambers are also used in the grain growing process.  A vacuum or inert atmosphere would be required as any oxidizing atmosphere would cause metal oxides to form, preventing the pure metal atoms from bonding (repairing cracks).

As a metallurgist, I find this interesting, but they are a long way from a viable industrial process of repairing fatigue damage.  Nano technology is they way of the future.