The development of the face-centred cubic interference functions as crystals grow

The development of the Debye interference function as the size of the coherent cluster increases is studied for crystals with face-centred cubic structure. The interference function is evaluated for assemblies of similar, randomly oriented parallelepipeds each containing n 3 atoms, 2 ⩽ n ⩽ 9. Even when n = 9, a total number of N = 729 atoms, many rings are absent and the topology of the interference function characterizes the crystal size. The application of these results to electron diffraction studies of nucleation in face-centred cubic metals is also discussed.