shows both DO22 and Dla superlattice reflections. There

is still streaking present through the DO22 reflections,

as in Figure 5.3a. Figures 5.5b and 5.5c are g = 1/5

(420) and g = 1/4 (420) dark field images. The beam

direction was approximately parallel to a B=[121]

direction. The figures show that both phases are randomly

distributed throughout the gamma phase. The D022 phase

has coarsened.

 After 10 hours, all three NixMo phases are present.

The D022 and Dla phases continue to grow, and the Ni2Mo

that is present is very sparsely distributed, even to the

extent that it may not appear in selected area and Riecke

method diffraction patterns.

 Aging for 100 hours results in almost complete

ordering throughout the gamma phase by the NixMo

precipitates. All three metastable NixMo phases are

present as evidenced by the B = <100> diffraction pattern

shown in Figure 5.6a. As after ten hours aging, the two

dominant phases are Ni3Mo D022 and Ni4Mo Dla. Figures

5.6b and 5.6c are B = [001], g = 1/4 (420) and g = 1/5

(420) dark field images of the D022 and Dla phases,

respectively. The Pt2Mo phasse is shown in Figure 5.6d, a

B = [001], g = 1/3 (420) dark field image.

 In addition to the three metastable NixMo phases, the

disordered gamma phase, and the cuboidal gamma prime