China
Africa
Explore chapters and articles related to this topic
Main components of the dislocation structure and the role of the dimensional factor
Published in A. M. Glezer, E. V. Kozlov, N. A. Koneva, N. A. Popova, I. A. Kurzina, Plastic Deformation of Nanostructured Materials, 2017
A. M. Glezer, E. V. Kozlov, N. A. Koneva, N. A. Popova, I. A. Kurzina
The scalar dislocation density decreases with the decreaseaterials grain size of the microlevel. This is accompanied by the increase of the curvature‐torsion of the crystal lattice (Fig. 3.23), the density of geometrically necessary dislocations and the internal stresses [69]. As this is accompanied by a decrease of the dependence of the scalar dislocation density, it is necessary to answer the question what is the reason for the increase of the curvature‐torsion of the crystal lattice and the internal stresses. Since the scalar dislocation density decreases, this phenomenon may be caused by the increase of the density of partial disclinations. The decrease of the density of dislocations does not indicate the formation of defect‐free grains, fragments, etc. In many cases, especially in nanomaterials, the decrease of the scalar density of the dislocations is compensated by the increase of the density of disclinations. In the ultrafine‐grained polycrystals, they are preferentially distributed in the triple and quaternary junctions of the grains [70,71].
Les vertus des défauts: The scientific works of the late Mr Maurice Kleman analysed, discussed and placed in historical context, with particular stress on dislocation, disclination and other manner of local material disbehaviour
Published in Liquid Crystals Reviews, 2022
Defects are local breakings of symmetry in an ordered medium. The physics of defects has long been reduced to the study of dislocations in solids, and to the main physical phenomena they are responsible for, like plastic deformation. Dislocations break translational symmetries. Disclinations break rotational symmetries and are the basic defects of media with continuous symmetries, like liquid crystals. In this review, it is stressed how their study has contributed to a renewal of the physics of defects ….