This was very interesting and certainly deserves more experimentation and analysis. Even so, I’m not expecting self-healing fractures in commercial products in the near future. Fatigue fractures are almost always associated with plastic strain at the crack tip. That is, there is microscopic permanent deformation between the fracture surfaces. This means that when they are reassembled, there is not an exact mirror matching of the two surfaces. It’s reasonable to expect that surfaces must be in intimate contact in order to achieve this ‘healing’. So, even if partial healing occurs at the points of contact, the healed part will be weaker than the original since not all of the atoms, molecules, or crystals will be rejoined. It also must be warm enough that sufficient diffusion among the atoms will occur. It’s not very warm in outer space where the vacuum might be adequate.
In addition, a good percentage of fractures in the real world are associated with corrosion. This can range from reduced part thickness to stress corrosion cracking at crack tips. This also defies the ‘in a vacuum’ component of the experiment.
You are correct. Entropy, in our physical universe, almost always wins.
I drive a 2000 Camry after research proved it to be outstandingly engineered to last, but I give it the best synthetic oil and care because 24 years of fatigue can not be denied.
Right now this self-healing metal idea remains in the realm of science fiction as far as practicality goes. Lord knows all those bridges and other support structures that have had their maintenance finds stolen over the years would benefit from advanced technology.