Formation of antiphase-domain boundary tubes in B2 ordered alloys by cross-slip and annihilation of screw dislocations

Abstract

A detailed analysis of the cross-slip and annihilation of screw dislocations in B2 ordered alloys is carried out using anisotropic elasticity. The paths of the partial dislocations are calculated and it is shown that antiphase-domain boundary tubes with complex structures may be formed by the cross-slip and annihilation of screw dislocation dipoles with a suitable range of heights (e.g. for Fe-30 at.% A1 alloy from 70 to 200 Å). APB tubes thus formed usually have a height of a few multiples of the elementary jog height, and widths of 7–50Å in agreement with experiment. Image calculations (including the effects of the limited aperture, defocus and the lens aberration) for APB tubes with a complex cross-section give a good match with experimental results. The analysis also explains why APB tubes of such small heights are generally connected to edge dislocation dipoles of much larger heights.