THEORY OF DISLOCATION MOBILITY IN PURE SLIP
The mobility during glide of uniformly moving dislocations or dislocation segments supposed not to be obstructed by any Peierl's barrier is estimated. It is shown that the energy dissipation associated with the strong anharmonicities in the core misfit plsne is negligible. For a straight freely moving dislocation, the thermoelastic and the phonon viscosity effect give rise to a drag stress at ordinary temperatures T approximately theta , theta being the Debye temperature, of the order sigma approximately (1/10) epsilon x (V/C) in insulators. In metals the thermoelastic effect is negligible, while the phonon viscosity effect will be of the same order of magnitude as in insulators. In the formula, epsilon = thermal energy density, V = dislocation velocity, and C = velocity of shear waves. The scattering of phonons by the dislocation causes a drag stress at ordinary temperatures of the order of magnitude of the above formula. All of the contributions to the drag stress go rapidly to zero with decreasing temperature. However, if the dislocation is constrained by the Peierl's barrier except at freely moving kinks, the kink mobility determines the dislocation mobility. It is shown that the scattering of phonons of a half-wave length larger than the kink width causes a drag stress outweighing all other contributions, and which persists with decreasing temperature as T down to a temperature (b)/(D) approximately , where b = the lattice spacing constant and D is the kink width. (auth)
- Research Organization:
- Carnegie Inst. of Tech., Pittsburgh. Metals Research Lab.
- DOE Contract Number:
- NONR 760(08)
- NSA Number:
- NSA-15-021070
- OSTI ID:
- 4065205
- Report Number(s):
- NP-10183
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- United States
- Language:
- English
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