Each journal hosts its own papers, but can also provide access to every other paper from journals they work with.

I think what they mean is every journal behaves like an instance on lemmy, federated with eachother. One journal not living up to your standards, block them on your instance etc. Like lemmy

Metals are made of crystals, they usually defourm along the grain boundaries and fatigue cracks also grow along them. By eliminating those boundaries you reduce the chance for fatigue cracks and make the overall blade stronger.