Abstract
Brown's bowing and passing model for persistent slip bands (PSBs) was extended in Cu and Ni to the whole range of temperatures in which a saturation plateau is observed. Advantage was taken of the similitude relation to rewrite in dimensionless form the equations of the original model and of a more accurate revisited version. Input quantities for computing the solutions were taken from a previous study of experimental results; all unknown quantities could then be directly calculated without any assumption or approximation. The comparison between experimental results and the predictions of the revisited model confirms the basic assumptions of the bowing and passing model, according to which the thermally activated annihilation of screw dipoles is governing the channel widths, the Orowan stresses and the critical stresses in the channels. All other assumptions and numerical predictions are perfectly confirmed, save for the occurrence of small resistive stresses in the channels. In addition, a better understanding of the complex behavior of PSB walls under stress is necessary in order to accurately determine the plastic strain amplitude of PSBs. Mesoscale and atomistic simulations are needed for further modeling of the wall properties and the screw dipole annihilations.
Highlights
Persistent slip bands (PSBs) are formed in ductile materials cycled in single slip at imposed plastic strain amplitudes per cycle typically between 10-4 and 10-2
Advantage was taken of the similitude relation to rewrite in dimensionless form the equations of the original model and of a revisited model, which is more accurate
The comparison between experimental results and the predictions of the original and revisited bowing and passing models were discussed in the previous sections
Summary
Persistent slip bands (PSBs) are formed in ductile materials cycled in single slip at imposed plastic strain amplitudes per cycle typically between 10-4 and 10-2. The obtained results were confronted to the predictions of Brown's bowing and passing model [9], according to which the critical flow stress of PSB channels is governed by the annihilation of screw dipoles by cross-slip. This critical stress is defined as the stress corresponding to the maximum height of stable dipoles, that is, to their passing stress. This makes it possible to predict without any approximation the values of all the relevant quantities as a function of flow stress and temperature.
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