The strain field and work-hardening from antiphase boundary tubes in ordered alloys

Abstract

The materials inside an antiphase boundary (APB) tube is shifted by half a lattice spacing along the axis of the tube; it is also compressed by the APB and, therefore, has the strain field of a line of dilatation. This strain field shears the surrounding material in plane strain. Tubes may be imaged in the electron microscope by any reflection vector except a fundamental vector parallel to the tubes. The stress field of a tube interacts strongly with some dislocations but not with the particular dislocations from which the tube could be formed. Tubes work-harden ordered alloys in a number of ways: (i) by dragging on primary edge dislocations, (ii) by modifying the cross-slip probabilities of primary screw dislocations, (iii) by direct stress field interaction with secondary coplanar dislocations and (iv) by acting as a forest to other secondary dislocations.