183
qualitative way that were measured in a semiquantitative
way using the energy dispersive method.
6.6 Conclusions
a) Aluminum stabilizes the DO22 phase in both RSR
197 and RSR 209.
b) Tungsten offsets the effect in a) in RSR 209.
c) Tantalum exerts no effect on the aging behavior
of RSR 197.
d) The partitioning of the quaternary elements can
be determined by quantitative EDS measurements.
These elements are shown to partition as
follows:
1) Ta partitions almost entirely to the gamma
prime phase and
2) W partitions equally between the gamma and
gamma prime phases.
e) The DO22 and Dla phases in RSR 197 aged at 760
are closely related crystallographically and are
shown to share a common 420 plane at their
interfaces.
f) This study has shown that convergent beam
electron diffraction, convergent beam
microdiffraction, and energy dispersive x-ray
analysis provide unique and relevant information
about the microstructures of these superalloys.