Small Angle Scattering from Dislocations in Deformed Single Crystals

It is shown that in spite of the occurrence of double Bragg scattering effects small angle scattering of x‐rays from dislocations in cold‐worked crystals should be observable, provided face‐centered cubic crystals deformed in tension at low temperature are used. In stage II of the stress‐strain curve the dislocation arrangement is essentially that of piled‐up groups. The small angle scattering from such groups has been worked out, treating both the first‐order (linear elastic theory) and second‐order (nonlinear elastic theory) effects. The first‐order effect dominates if the scattering vector g is normal to the glide‐plane, whereas the second‐order effect dominates if g lies in the glide‐plane. If both effects can be observed, interesting information on the density and the arrangement of dislocations can be derived.