Electron Diffraction and Electron Microscopic Study of Long‐ and Short‐Range Order in Ni₄Mo and of the Substructure Resulting from Ordering

The ordering process in Ni₄Mo gives rise to three different classes of interfaces within a single crystal of the basic structure. The geometry of these interfaces and the diffraction effects to be expected from them are discussed. Evidence for the different classes of interfaces is given. The interfaces resulting from slip are discussed and compared with the observations. Quenched specimens exhibit short range order. A model for short range order in this alloy is presented. Preliminary experiments indicate that quenched Ni₃Mo also shows short range order of a similar type as Ni₄Mo.