Publication | Closed Access
On the nature of the 'short-range order' in 1 1/2 0 alloys
86
Citations
0
References
1985
Year
Observed Diffuse IntensityEngineeringMicroscopyElectron Diffraction'Short-range OrderElectron MicroscopyMaterials ScienceMaterials EngineeringPhysicsCrystalline DefectsHigh-resolution Electron-microscope ImagesMetallurgical InteractionMicroanalysisCrystallographySolid-state PhysicMicrostructureX-ray DiffractionApplied PhysicsCondensed Matter PhysicsAlloy DesignAlloy PhaseMetallurgical System
High-resolution electron-microscope images of the (1½0) special-point short-range-ordering alloys NiaMo, Au4Cr, AuaV and muaFe are compared, and the extent to which optical diffractograms from local regions of such micrographs can be interpreted is discussed. For Au4Cr and Ni4Mo, the observed state or order can be interpreted as being due to the presence of microdomains of the D022 structure and elements of the Dla structure, extending sometimes several unit cells along the c direction, but being quite often only one or a small number of unit cells wide. For Au4V and Au4Fe, the observed diffuse intensity is probably too weak to allow decisive conclusions. It is argued that the 'microdomain' model and the 'concentration-wave' model are two descriptions of the same physical reality which are revealed by different imaging modes. A reinterpretation of some results obtained by X-ray diffraction on NiaMo by Chakravarti, Starke, Sparks & Williams [J. Phys. Chem. Solids (1974), 35, 1317-1326] confirm the proposed model.