of the aforementioned antiphase boundaries are

indistinguishable.

2.3.4.1. D022: Ni3Mo

 There are three easily differentiated variants in the

D022 structure, each corresponding to the c axis of the

D022 being parallel to one of the cube axes of the parent

FCC lattice. This is shown in Figure 2.17a. All three

variants may be visible simultaneously. Indexed [001] and

[T12] diffraction patterns are shown in Figure 2.19b.

2.3.4.2 Dla: Ni4Mo

 Six distinguishable variants of Ni4Mo are possible.

These correspond to the tetrad axis of the Dla being

parallel to the parent FCC cube axes (three variants) and

further, the a axis of the Ni4Mo rotated cw or ccw about

the c axis relative to each FCC cube axis. Only two of

the six distinguishable variants will be visible along any

B = 100 imaging condition. These two are the single

axis clockwise and counterclockwise rotated variants shown

in Figure 2.18a. The B=[100] indexed diffraction pattern

corresponding to these two real space variants is shown in

Figure 2.18b. Indexed B = [001] and B = [112] Ni4Mo

diffraction patterns are shown in Figure 2.19c.