Dislocation climb

Solution. Substitutional atoms of type 1 may diffuse more rapidly than atoms of type 2 if they diffuse independently by the interstitialcy mechanism in Fig. 8.4. To sustain the unequal fluxes, interstitial-atom defects can be created at climbing dislocations acting... 

Vacancy quenching experiments where the destruction rate at climbing dislocations of supersaturated vacancies obtained by quenching the metal from an elevated temperature is measured (see the analysis of this phenomenon in the following section)... 

Sintering experiments where the rate at which vacancies leave voids and are then destroyed at climbing dislocations is measured... 

Climbing Dislocations as Sinks for Excess Quenched-in Vacancies. Dislocations are generally the most important vacancy sources that act to maintain the vacancy concentration in thermal equilibrium as the temperature of a crystal changes. In the following, we analyze the rate at which the usual dislocation network in a... 

Atoms diffuse through the crystal from climbing dislocations. Equivalently, vacancies diffuse from the surface. 

Figure 16.12 Idealized array of edge dislocations subjected to applied stress, a. Arrows show stress-induced diffusion current around each climbing dislocation.

Figure 9.27. Climbing dislocations and loop debris associated with (0001) slip in dolomite deformed at 800°C. (From Barber et al. 1981.)...

Large quantities of secondary slip must have occurred, as well as dislocation climb. Dislocation nodes of the type 1/2(110) + 1/2(I01) + l/2(0ll) are... 

In this case, the strain rate is determined by the rate of emission or absorption of vacancies. Figure 11.5 shows the example of two edge dislocations pinned at two obstacles. Dislocation 1 has to absorb vacancies to climb dislocation 2 needs to emit them. Thus, vacancies can be transported from one dislocation to the other, with one dislocation acting as vacancy source, the other as vacancy sink. The vacancy current density, j, determines the rate of deformation. This quantity can be estimated. 

In dislocation climb/dislocation glide, the stress applied to the crystals activates dislocations to run through the crystal, thus moving the crystal layers upon each other. This deformation occurs at high stress levels and is very fast (Fig. 2). 

Constant dislocation climb/dislocation glide (DC) 3.5 X 1Q25... 

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