Kink pair nucleation and critical shear stress

Modeling defects and plasticity in MgSiO3 post-perovskite: Part 3—Screw and edge [001] dislocations

“…The kink-pair formation mechanism is commonly investigated based on the line tension (LT) model (Guyot and Dorn 1967), the kink-kink (KK) interaction model (Seeger and Schiller 1962) or on the elastic interaction model (Koizumi et al 1993(Koizumi et al , 1994. These models only differ by the way the ∆E el term is calculated.…”

“…Simultaneous motion of both partials allows assuming a simple sinusoidal shape of the Peierls potential. Therefore, the maximum energy barrier for each partial can be defined as (Koizumi et al 1993): (Goryaeva et al 2015b(Goryaeva et al , 2016 are 15 and 2 meV/Å for screw and edge dislocations, respectively. Although higher than for the [100] dislocations, lattice friction opposed to the [001] dislocation glide in (010) is still very low.…”

Multiscale modeling of plastic deformation of molybdenum and tungsten. III. Effects of temperature and plastic strain rate

“…This development is described in detail in Section 3. Furthermore, the region of the potential where the Peierls barrier reaches its maximum, which is not sampled in 0 K calculations, is chosen to be flat as suggested by the analysis of the effect of this region on the temperature dependence of the yield stress in [41][42][43].…”

“…reaches its largest value far away from this maximum and thus equation (7) that provides for the input of data from atomistic studies conveys no information about the Peierls barrier near its maximum. Auspiciously, a helpful information about this region of the Peierls barrier was obtained in [41][42][43] where the thermally activated formation of kink-pairs for various shapes of the Peierls barrier was investigated. The best agreement between calculated temperature dependence of the yield stress and experiments was attained when the top of the Peierls barrier exhibited a flat plateau or even an intermediate local minimum.…”

Peierls barriers of a-type edge and screw dislocations moving on basal and prismatic planes in magnesium

“…A more elegant solution of this problem is to develop thermodynamic models of slip that provide the dependence of the activation enthalpy on the applied stress, its character and orientation. The most prominent models developed to date are those by Seeger [13], Dorn and Rajnak [14], Celli et al [15], Koizumi et al [16] and Suzuki et al [17]. The adjustable parameters in these models have to be determined by higher-level calculations, typically by a number of molecular statics simulations of isolated dislocations under stress [18].…”