The Mechanical Properties of Metals

TLDR

Dislocations in close‑packed cubic lattices and the Frank‑Read mechanism explain the origin of slip bands. The paper speculates on the stability of deformation bands. The study demonstrates that Frank‑Read sources produce cross‑slip and deformation bands, that vacancy generation by dislocations drives polygonization, recovery, and steady‑state creep, and that the high stresses in these bands enable diffusion at otherwise inaccessible temperatures, with low‑temperature creep occurring without recovery.

Abstract

A description is given of edge and screw dislocations in a close-packed cubic lattice, which leads up to an account of the theory of Frank and Read of the origin of slip bands. Consideration is then given to a crystalline grain containing Frank-Read sources; it is shown that one has to expect cross-slip and the formation of deformation bands. It is shown moreover that the formation of vacancies by moving dislocations plays an essential role in these processes. Some speculations on the stability of deformation bands are given. It is suggested that the movement of vacancies (self-diffusion) plays an essential part in polygonization, recovery and steady-state creep, enabling dislocations in deformation bands to move out of their slip planes and so relieve stress. It is probable moreover that in these bands the stresses are several hundred times greater than the applied stress, and that this enables diffusion to occur at temperatures at which it would not be possible otherwise. Finally an account is given of low temperature creep of the type which does not involve recovery.