The Low Angle Grain Boundaries have misorientation angles between the adjoining grains below 13-15˚, that can be described by a an array of dislocations. The CSL boundaries concept is a geometrical classification of singular high angle grain boundaries (HAGB). Some of these GB present special characteristics, like diffusion, energy, creep deformation, etc. The concept is that when GBs have a high density of coincident sites, considering the interpenetrating lattices of the adjoining grains, the grain boundary energy is lower than the general grains. One classic example is a annealing twin of a medium to low stacking fault energy material.

Thank you @Leonardo, for your answer. May you please tell me more about the correlation between CSL density and creep properties? What i know, higher is better than for creep, but why researchers don't focus on this type of interfaces to provide exceptional creep properties?

What extent do need to increase CSL?

And how can to introduce and control CSL?Is there any wellknow processes or heattreatment process to increase its density?