Characterization of domain boundaries in Ni₄Mo by convergent beam electron diffraction

The alloy Ni-20 at.% Mo (Ni₄Mo) is disordered (α) above 868°C and ordered (β) below this temperature. Upon the formation of β from the α, a variety of interfaces between the ordered domains is formed. Characterizing the domain interfaces by using conventional selected-area diffraction can be difficult since, in some orientations, superlattice diffraction spots are identical with those of the α-phase. However, convergent beam electron diffraction can be used to examine the higher-order Laue zone patterns, in which superlattice spots can be revealed, Also this technique produces the diffraction pattern from a very small analysis area. We have used this method to identify some of the characteristics of domain boundaries in the ordered Ni₄Mo alloy.