5.1.7 Special Aging/Special Alloys
5.1.7.1 Alloy #17 -- Solution Heat Treated, Quenched
 and Aged at 760 C for 100 Hours

 An image of this ternary alloy along a B = <112>

direction is shown in Figure 5.27c. The microstructure of

this alloy is essentially identical to the RSR alloys.

This would be expected since both the RSR alloys and the

cast alloys were solution heat treated prior to aging.

 After the 100 hour heat treatment, the phase

distribution is similar to the phase distribution in RSR

197 after a similar thermal treatment (see section

5.1.4.1). Figure 5.27a is a B = (100> selected area

diffraction pattern. This pattern should be compared with

Figure 5.6a. Figure 5.27b is a combined g=1/4(420),

g=1/5(420) dark field image showing the similarity in the

precipitate morphology between the D022 and Dla phases in

this ternary alloy and RSR 197, aged for the same time.

5.1.7.2 Alloy #17 -- Solution Heat Treated, Quenched
 and Aged at 870 C for 100 Hours

 Figure 5.28a is a B = [001] two beam image showing a

well developed interfacial dislocation structure. Figure

5.28b, a B = (100> selected area diffraction pattern shows

that no metastable phases are present at the aging

temperature. This sample was water quenched after aging.

The RSR alloys were all air quenched after aging.