During 1/3(2110) (0001) basal slip in Sapphire, the basal dislocation have been found to dissociate into two partials se

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During 1 3 2110 0001 Basal Slip In Sapphire The Basal Dislocation Have Been Found To Dissociate Into Two Partials Se 1 (160.17 KiB) Viewed 29 times

During 1/3(2110) (0001) basal slip in Sapphire, the basal dislocation have been found to dissociate into two partials separated by a stacking fault according to the following dislocation reaction 1/3 (2110)→1/3[1100]+1/3[100] =b¹ + b² (4-1) For the case of an edge dislocation and using an orthonormal coordinate system in which the dislocation line direction is along the 2-axis (or 5 = [001]), the basal glide plane is n = (010) the and the Burger's vector of the two partial dislocations are b¹ = = 2 [1.0, and b² = 2 [1,0,- respectively, where b=0.475 [nm] is the magnitude of the basal slip dislocation.. a) (5 p) If the stacking fault energy on the (0001) basal plane is BP = 2.0[J/m²], determine the separation distance between the two glide partials (see Fig. 4a). From your results, should the dissociation be considered to be core spreading or a well determined dissociation? b) (5 p) Electron microscopy has been used to determine that basal dislocations dissociate normal to the glide plane via self-climb (i.e., the stacking fault is on a (2110) prism plane) (see Fig. 4b). If the stacking fault energy of the prism plane is pp = 0.15[J/m²], determine the determine the equilibrium separation distance between the partials. Fig. 4a Fig. 4bbA bB bª Stacking Fault IbB Note: The interaction forces are best determined using the Peach-Koehler equation. The lattice parameters, shear modulus and Poison's ratio for Sapphire are: a=0.475 [nm], c=1.299 [nm], u=150[GPa], and v=0.25, respectively. (0001) Glide Plane (2110) Self-Climb Plane