Small Angle Scattering by Dislocations

Published

March 1, 1998

Author(s)

R Thomson, Lyle E. Levine, Gabrielle G. Long

Abstract

It is shown that the small-angle scattering of x rays or neutrons by dislocations in a deformed metal, which are partially ordered into wall-like structures, is characterized by several structure factors. Principally there are associated with 1) a single dislocation of dipole, 2) the dislocation configuration in the plane of the wall, and 3) the distribution of dislocations across the wall thickness. The scattered intensity is dominated by dislocations which lie perpendicular to the scattering vector, q, and reaches a maximum when q is normal to the slip plane of these dislocations. Above a particular |q|, the scattered intensity is sensitive only to the total edge dislocation content of the visible dislocations (i.e., scattering is incoherent), while below this value, the scattering is dominated by how the dislocations are distributed in walls. For walls normal to their slip planes, the structure factor will reflect the dislocation distribution in the plane of the wall, while for walls parallel to their slip planes, the distribution in the thickness direction will be visible. Therefore, even though a deformed material is composed of complicated dislocation structures, only those segments conforming to these rather strict prescriptions will be singled out for scattering, and by adjusting the beam/slip system geometry, any details of the structure can be determined experimentally.

Citation

NIST Interagency/Internal Report (NISTIR) - 6117

Report Number

6117

NIST Pub Series

NIST Interagency/Internal Report (NISTIR)

Pub Type

NIST Pubs

Keywords

dislocation scattering, dislocations, SAXS

Citation

Thomson, R. , Levine, L. and Long, G. (1998), Small Angle Scattering by Dislocations, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed October 31, 2024)