Long-range stress fields

Heterophase Interfaces. In certain cases, sharp heterophase interfaces are able to move in military fashion by the glissile motion of line defects possessing dislocation character. Interfaces of this type occur in martensitic displacive transformations, which are described in Chapter 24. The interface between the parent phase and the newly formed martensitic phase is a semicoherent interface that has no long-range stress field. The array of interfacial dislocations can move in glissile fashion and shuffle atoms across the interface. This advancing interface will transform... 

The long-range stress field about a dislocation loop also cancels and thus the strain energy of a curved dislocation is approximately Gb /4n) ln(p/ro), where p is the radius of curvature. " ... 

Fig. 8.9. Stress fields at the end of a trench etched in a 15f

It is often useful to describe the dislocation content of coherent and semicoherent interfaces in terms of another framework which employs coherency dislocations and anticoherency dislocations. The basic idea is illustrated in Fig. B.8, which shows the same two boundaries shown previously in Fig. B.76 and c. The coherency dislocations possess a stress field equivalent to the long-range coherency stresses associated with the coherent interface. They are not real dislocations in the... 

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