Prismatic slip in hexagonal close-packed metals was studied by calculating the thermally activated motion of a 1/3[11▪0] screw dislocation in a 2-dimensional Peierls potential which was assumed to act in the (11▪0) plane. The kink-pair formation process for the transition of a dislocation from one stable position to another under an applied stress was investigated, and the activation energies for the 2 types of transition which constituted prismatic slip were calculated. By using these activation energies, the critical flow stress was deduced as a function of the direction of the applied stress and the temperature. The calculated relationship between critical flow stress and direction of the applied stress deviated significantly from the Schmid law, but reproduced well the deviation which was observed in experimental data on Ti. The deviation from the Schmid law arose from an inherent structural feature of the hexagonal close-packed lattice: that is, a zig-zag arrangement along the prismatic plane of atomic rows.

Thermally Activated Motion of a Screw Dislocation Overcoming the Peierls Potential for Prismatic Slip in an HCP Lattice K.Edagawa, T.Suzuki, S.Takeuchi: Japanese Journal of Applied Physics - 1, 1998, 37[7], 4086-91