5. In conclusion

This second article on the real grain boundary (see previous [M 4 012] ) emphasizes the importance of intergranular defects and their interactions in the response of joints to any mechanical loading. But this influence is not limited to mechanical properties, it also affects corrosion, fracture, electrical activity... Understanding the micromechanisms that control the role of grain boundaries and their defects in different material properties is a first step in the direction of "grain boundary engineering".