Burgers Vector Component Research Articles

Deformation of internal boundaries

A geometrical analysis of the deformation of internal boundaries is presented using the slip systems as reference co-ordinate axes to describe the orientation of the two phases adjacent to the boundary. The present analysis can be applied to any type of boundary such as a grain boundary, a twin boundary or a two-phase interface. The nature of the disturbance left by a dislocation cutting through the boundary is characterized by a boundary dislocation, the Burgers vector of which can be determined from the orientation relationship between the adjacent slip systems. Whenever the crystal dislocation, cutting through the boundary, has a Burgers vector component normal to the boundary, the disturbance also possesses a ledge character, the motion of which may cause both grain boundary sliding as well as migration. The formulae derived are applied to simple cases to determine the nature of the boundary dislocations.

Deformation structure of?-SiC single crystals

The deformation ofα-SiC single crystals in bending with the direction of extension and compression approximately parallel to the basal face (the axis of bending parallel to (0001), T = 2000–2100°C) involves slip over the basal plane; the directions of slip are and . Accordingly, crystallographic planes rotate about parallel axes, and . Slip in the direction may be a consequence of migration of dislocations with Burgers vectors equal to b=2/3 (a full dislocation and\(\overrightarrow b = 1/3\) (a partial dislocation). X-ray microdiffraction observations show [12] that partial dislocations with Burgers vector components parallel to [101¯1] frequently form inα-SiC; travel of partial dislocations apparently plays an important part in the deformation of α-SiC. The deformation ofα-SiC is accompanied by kink band formation [1].

Intersection Faulting Mechanism Theory of Flow and Fracture of Face-Centered Cubic Metals

The intersection of any dislocation avalanche with a stationary dislocation having a Burgers vector component normal to the slip plane is shown to produce a close-packed partial plane of vacancies or interstitials in the slip plane, intrinsic or extrinsic faults for {111} slip planes. These faults have high energy in non-close-packed planes, consistent with observed slip plane preference. The mechanism gives improved understanding of recent x-ray results. Metallographic slip observations are consistent with the hypothesis that the etch indications are occurring at faults produced by the present mechanism. Fracture is postulated as resulting from the growth of "head-on" faults until transition occurs to the Griffith mechanism. Fault correction by partial slip produces additional dislocations, some potentially active as Frank-Read sources in the other slip planes. For copper, intrinsic or extrinsic faults are estimated to have energies of 40 ergs ${\mathrm{cm}}^{\ensuremath{-}2}$ and maximum widths of 400 A.