An Analysis of Cell Formation due to Plastic Deformation Based on Dislocation Theory

Abstract

Two kinds of dislocation configurations have been observed in transmission electron microscope studies of crystals subjected to plastic deformation. One is uniform arrangement of dislocations and the other is cell structure. The former is observed at an early stage of plastic deformation and the latter is usually observed at high plastic strains.
Many different views have been proposed to account for the reason why the cell structure is formed in crystals subjected to plastic deformation. In this paper, this problem is discussed with particular attention to conditions for the cell formation.
(1) The critical dislocation density above which cell structure is formed, (2) the change in dislocation configuration with the growth of cell structure during creep deformation, and (3) the change in average internal stress during creep deformation, were estimated from the calculation based on the following assumptions: dislocations arrange themselves so that the strain rate becomes maximum in creep deformation and so that the applied stress becomes minimum in tensile deformation.
The results of calculations obtained were in fairly good agreement with experimental ones reported hitherto. Therefore, it is concluded that one of the reasons for the cell formation is that dislocations arrange themselves according to the assumptions mentioned above.