149
are also some elongated dark rods here that do not index
as N2M0. They are identified in Section 5.1.6.3.
NiMo can be found on the grain boundaries. Figure
5.24b is an example of the NiMo on the boundary between
the cellular gamma prime and the grain boundary itself.
A NiMo B = \100X> diffraction pattern is indexed in Figure
5.24c. An interfacial dislocation network has developed,
as shown in Figure 5.24b.
5.1.6.3 Solution Heat Treated, Quenched, and Aged
at 870 C for up to 100 Hours
The processes observed to be taking place after 100
hours at 810 C are already advanced after 1 hours aging
at 870 C. Numerous inter-gamma prime platelets have
precipitated, as shown in Figure 5.25a. This figure also
shows a well developed dislocation structure. The N2M0
Pt2Mo is still present, as shown in the convergent beam
microdiffraction pattern, Figure 5.25b. The consequence
of increasing the aging time to 100 hours at this
temperature is to coarsen the precipitate that was
observed at the shorter aging time. Figure 5.25c shows
that the rod-like recipitate occupies most of the
intercuboidal region. X-ray diffraction patterns identify
this precipitate as Mo. Two convergent beam
microdiffraction patterns from one of these precipitates
indexed as Mo are shown in Figures 5.26a and 5.26b.