Dislocation Defects.docx

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Dislocation defects  A dislocation is a linear or one-dimensional defect in which some of the atoms in the crystals are misaligned or their arrangement is in irregular pattern.  There are different types of dislocation in solid some of them are dislocation and mixed dislocation.

screw dislocation, edge

 In edge extra-half-plane of atom is added within crystal.  In screw dislocation the upper region is shifted by distortion of one atom distance relative to bottom portion.  In mixed dislocation both the edge and screw defects is present.  In this paper we present a detail approach for the characterization of dislocation, dislocation segment and dislocation networks, resulting in accurate quantification and significantly increasing the insight into the dislocation structure. Dislocation networks in metals consist of dislocation segments, pinned by microstructural obstacles. In the present paper a model is introduced that describes the behavior of these dislocation segments in the pre-yield range of a tensile test on the basis of fundamental concepts of dislocation theory. The model enables experimental quantification of the dislocation density and segment length from the tensile curve. Quantitative results are shown and discussed on the development of the dislocation network as a function of increasing degree of plastic deformation, including validation and physical interpretation of the classical Taylor equation. Some graphs are also given in the paper which is obtained through experimental data. Also some mathematical equations are given which are widely used to solve our problem of dislocations in materials.