Dynamic model of the wall structure in persistent slip bands of fatigued metals II. The wall spacing and the temperature dependence of the yield stress in saturation

It is suggested that the dislocation walls of persistent slip bands (PSBs) are elements with intrinsic features such as a characteristic width and a characteristic yield stress. The model predicts that the properties of the walls show only a weak temperature dependence. The observed remarkable temperature dependence of the yield stress of PSBs (plateau stress) is attributed to the mechanisms by which new walls are nucleated in the channels. The model takes into account the populations of the edge dislocations, of the screw dislocations and of the point defect agglomerates. The constitutents of the three populations have characteristic lifetimes. It is concluded that the short-living screw dislocations adapt themselves to the behaviour of the longer-living edge dislocations and point defect agglomerates which accordingly determine the features of a PSB.