Mechanism Frank-Read

Figure 10.9. The Frank-Read dislocation loop mechanism of dislocation multiplication. A shear stress causes the portion of a dislocation that is between two pinned segments to bow outward on the slip plane (indicated by arrows). Eventually, the dislocation loop reaches the configuration shown in the middle. When the two curved segments meet, the dislocation loop is freed and a new loop is formed to continue the process.

Fig. 22. Dislocation multiplication by a Frank-Read mechanism with single pinning, (a) and (b) and with double pinning, (c)-(f).

The other important multiplication, which takes place via cross glide, occurs more readily than that which operates through the classical Frank-Read mechanism. In a dislocation loop, that part of the line which has a screw orientation can move out from its slip plane (compare... 

Figure 6.11 A pinned segment of a dislocation undergoing bowing under the action of a shear stress. A dislocation loop forms as the bowing segments (X and Y) merge and the pinned segment returns. This mechanism allows dislocation multiplication and is known as a Frank-Read source.

Dislocation multiplication occurs when the dislocations are made to move during deformation. One possible multiplication mechanism is the Frank-Read source. Suppose that a dislocation is pinned at two points, which are a distance / apart, as shown in Figure 12.21a. Under the action of an applied stress the dislocation will bow out. The radius of curvature R is related to the applied shear stress. To. 

A mechanism of the double-cross slip mechanism is suggested for the generation of dislocations during deformation which increases the density in large amounts in addition to the known Frank-Read mechanism. 

Material load axis Burgers vector Slip planes cross slip planes Frank- read sources Double- cross slip mechanism... 

J. Frank, W. Huang, and B. Leimkuhler, J. Comput. Phys., 133, 160 (1997). 10. H. Goldstein, Classical Mechanics, Addison-Wesley, Reading, Massachussetts... 

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