Boundaries of grain-Regular structure of lattice

Question

Are the boundaries of grain are a continuation of regular structure of lattice from one grain to the other?

Answer 1

They are called boundaries since this is where one crystal interacts with the other. The lattice structure doesn’t continue across the interface devoid of mismatch. While there is some lattice, interaction or sharing it is not complete and there are various defects allocated with the boundaries. The degree of the mismatch finds out if the boundary is the high angle boundary (lots of the mismatch) or the low angle boundary (extremely little mismatch) A tilt boundary is an example of a low angle boundary. This is also one of the reasons that diffusion along grain boundaries is so much higher than through bulk crystal.