A so-called symmetrical low-angle boundary can be described as an assembly of edge dislocations (see figure 1). Figure 1: Schematic sketch of a low-angle boundary. 1. Estimate the specific grain boundary energy for copper with a 10 tilt angle, G = 40 GPa, and || = 4 x 10-0 m. Note: Make use of the fact that the energy of a dislocation can be assumed to be Ep = Gb. 2. Calculate the values for tilt angles of = 5 and 9 = 12. 3. Why is there a limit for the tilt angle of low-angle boundaries at about 15?