Dislocation Arrangements In Crystals Research Articles

Stereological analysis of dislocation arrangements in crystals from TEM images

AbstractIdeas of stochastic geometry have been used in order to develop procedures for stereological characterization of dislocation arrangements in crystals from TEM images. Two conceptions, which can be taken for promising in much cases, are presented in some detail: analysis of statistically homogeneous defect distributions by means of pair — correlation functions and interpretation of statistically inhomogeneous dislocation arrangements in terms of a so‐called Voronoi‐mosaic. Practical application of both methods is demonstrated by analysis of dislocation configurations occurring in metallurgy and solid‐state technology.

Deformation of FeAl single crystals at high temperatures

Abstract Single crystals of the intermetallic compound FeAl with the CsCl structure have been deformed in compression at temperatures between 470 and 1000 K to study the slip geometry and the dislocation arrangements in this material at high temperatures. At temperatures below 0·44 of the melting temperature, T m, slip occurs on the {110}〈111〉 systems, while at 0·44T m, the transitions in the slip directions from 〈111〉 to 〈001〉 takes place for orientations in the right-hand side of the unit stereographic triangle, i.e. near the [011]-[111] boundary and, as the deformation temperature is increased, the region showing the 〈001〉-type slip becomes wider. The critical resolved shear stress for both types of slip exhibits a strong temperature dependence above 0·44T m. The dislocation arrangements in crystals deformed by the slip of 〈001〉 type is found to consist mostly of edge dislocations. The occurrence of the 〈001〉-type slip at such a high temperature is suggested to be associated with compositional deviatio...

Photoelastic study of dislocation arrangements in crystals

Abstract The plastic deformation of single crystal bars of silver chloride in tension and bending has been studied by using the photoelastic effect. It is found that in tension the plastic deformation is not uniform over a given cross section but is greatest near the surfaces. In bending the plastic deformation is found to propagate longitudinally along the bars rather than transversely. The distribution of birefringence, and hence that of stress, has been measured and the result interpreted by means of a simple dislocation model. It is concluded that, in silver chloride, the ratio of the stress necessary to propagate dislocations to the stress necessary to generate them is less than about 0–6. The shear stress on the glide plane necessary to propagate dislocations is approximately 5–2 × 106 dynes/cm2.