Configurations of {100} dislocation walls formed during fatigue

Advancing towards constitutive equations for the metal industry via the LEDS theory

“…Dickson and co-workers [104][105][106][107] accept the previous analysis of the walls in terms of Taylor lattices composed of dipoles, [103] and that the actually occurring structures have minimum energy for a given dislocation content; i.e., they accept the LEDS hypothesis. Therefore, they consider how two sets of Taylor lattice domains represented by veins due to two different glide systems can be fitted together with minimum strain energy.…”

“…[103] Building on this result, Dickson and co-workers [104][105][106][107] showed that the morphology of maze structures always appears to approach minimum free energy of the dislocations in them. Specifically, the relative frequency of free wall ends as compared to L-and T-shaped wall joints is as expected from their (quite minor) differences in free energy on account of longer-range stresses.…”

The impact of F.R.N. Nabarro on the LEDS theory of workhardening

“…Among several outstanding supporting micrographical investigations is one by Charsley and Kuhlmann-Wilsdorf [68]. It illuminates still another dislocation structure type, namely so-called ''maze structures'' formed in multiple glide fatigue that superficially look like cell structures.…”

“…Specifically, the walls studied in Ref. [68] are parallel to {1 0 0} planes and thus are in mutually perpendicular orientation, and each comprise two mutually perpendicular Burgers vectors. The peculiar morphology of maze structures, at least in this case, arises because wall intersection are sites of heightened energy and therefore are [69] and Lepistö, Kuokkala and Kettunen [70] of which micrographs were included in the survey article [71], edited by Nabarro and Duesbery.…”

Assessment of Internal Stresses Using Dislocation Dipole Heights in Cyclically Deformed [001] Copper Single Crystals

“…The details of these dislocation structures strongly depend on the strain amplitude, crystal orientation, temperature, and number of cycles [1][2][3][4]. The labyrinth microstructure was first observed in a polycrystalline Cu-Ni alloy fatigued in multiple glide by Charsley and Kuhlmann-Wilsdorf [5] and then observed by Jin and Winter [6] for the first time in single crystals in cyclically deformed [001] oriented copper (multiple slip). The purpose of this work is to determine the microstructure of cyclically deformed copper single crystal oriented for multiple slip at ambient temperature along the [001] tensile axis and to measure the dislocation dipole heights across the heterogeneous dislocation microstructure.…”