An analytical method for determination of Gamma prime in Ni-base alloy (1.1Al-2.25Ti-14.7Cr-8.9Fe) has been studied using the potentiostatic method with the non-aqueous electrolyte.
The results obtained are summarized as follows.
(1) In order to extract quantitatively gamma prime from specimens, 3% nitric acid-2% perchloric acid-methyl alcohol electrolyte and +1300 mV vs SCE are recommended as an electrolyte and electrolytic potential, respectively.
(2) In order to determine the elements in extracted gamma prime, a rapid method is established. Nickel is determined by a volumetric method or ICP method. Aluminium, titanium, chromium and iron are determined by a ICP method.
(3) The analytical results of gamma prime was found to be about 5% in the as cast specimen.
The percentage of gamma prime increased according to the aging time at 973 K up to 15.5% after 3.6 Ms aging.
(4) The percentage of nickel in the extracted residues increased according to the aging time.
On the contrary, those of titanium, aluminium and chromium decreased gradually but that of iron remained constant. According to the analytical results, the chemical composition form of gamma prime in the specimen was represented as Ni
2.88Al
0.37Ti
0.51Cr
0.12Fe
0.12 in case of the 360 ks aging specimen, if the form was assumed as Ni
3(Al, Ti).
(5) Gamma prime grew up according to the aging time up to about 40 nm after 3.6 Ms aging.
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