SMALL-ANGLE NEUTRON-SCATTERING FROM ANISOTROPIC SINGLE-CRYSTALLINE MATERIALS

'Isotropic' small-angle scattering (SAS), i.e. without azimuthal depen dence around the primary beam, occurs only for specific configurations of the scattering objects if single-crystalline material is studied. For decomposing Ni-based alloy single crystals, SAS signals are genera lly highly anisotropic. From analysis of two-dimensional SAS patterns, important information on the evolution of the morphology and on the t hree-dimensional spatial arrangement of the precipitates from the earl y stages of decomposition can be extracted. The real-space information obtained from transmission electron microscopy is an excellent comple ment to the reciprocal-space information extracted from SAS data. The complementary use of these two techniques offers a valuable approach t o the study of precipitation phenomena.