“What happens when multiple grains in a crystal collide?”
Polycrystalline materials have grains that flow in numerous different directions. However, to make a continuous object, these grains must coalesce with one another. So what exactly happens at this grain boundary? Well, believe it or not, these grain boundaries actually cause the strength of the material to increase! The reasoning for this is that fragmentation along a material occurs across a row in a crystalline grain, so anything that limits this row will act as a dampener to the system.