Frank sessile dislocation

Figure 3.15 Change of stacking across a dislocation loop in a face-centered cubic structure. The structure is that of a Frank sessile dislocation loop.

Fig. 21. Defects formed by condensation of vacancies onto dislocation loops formed by collapse of small vacancy clusters, (a) Dislocation loops in 99.999% Al, quenched from 610°C into liquid N2, then aged 1 hr at — 80°C and 2 hr at 60°C. The defect is a Frank sessile dislocation enclosing an intrinsic stacking fault. Magnification 27,000 x. From Dr. K. Y. Chen, Northwestern University, Evanston, Illinois, (b) Stacking fault tetrahedra in 99.999% Au quenched from 1038° into -35°C brine and aged at 25°C. The tetrahedra (some are truncated) are bound by intrinsic stacking faults and dislocations at the edges called stair rod dislocations. Magnification 70,000 X. From Dr. J. A. McComb, Northwestern University, Evanston, Illinois.

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