A study by means of electron microscopy and electron diffraction of vacancy ordering in ternary alloys of the system AlCuNi

The structure and microstructure of ternary alloys in the system Al(Cu, Ni)1–x are studied by means of selected area electron diffraction and by means of lattice imaging. The long range ordered structures are derived from the CsCl structure, one of the sublattices being occupied by aluminium, the other one by metal atoms and vacancies. A number of composition related superstructures occurs; they are all based on the ordering of vacancies and metal atoms in (111) layers. A “transition” state can be identified in rapidly cooled specimens.