PSI - Issue 81

Anatolii Klymenko et al. / Procedia Structural Integrity 81 (2026) 470–477

475

In the near-surface layer of the alloy, one can observe the presence of lead (up to 17%) and a low concentration of oxygen (up to 7%), which may indicate the formation of intermetallic compounds of lead with nickel. With an increase in the duration of the tests to 1440, traces of lead melt can be observed in the base metal of the alloy at a depth of up to 20 μm , which is probably due to dilution or oxidation of the grain boundaries of the alloy and diffusion into the formed defects of the lead melt, see Fig. 5c.

Element, Weight %

O Al

Cr

Fe

Ni

Pb

Spectrum 1 Spectrum 2 Spectrum 3 Spectrum 4 Spectrum 5 Spectrum 6

4.53 1.13 4.76

- -

-

- -

0.90 94.01 95.96 1.91

0.28 2.83

0.24

2.72 60.73 27.75

14.81 0.49 10.07 5.68

4.37 64.57

2.75

0.25

4.21

3.82 75.08 13.89

-

1.12 24.12 14.24 60.51

-

Element, Weight %

O Al

Cr

Fe

Ni

Pb

Spectrum 1 Spectrum 2 Spectrum 3 Spectrum 4 Spectrum 5

0.44

1.20 23.42 14.09 60.85

-

14.28 0.71 12.01 7.31 25.89 39.80

14.98 0.47

8.29

5.03 10.11 61.12

17.76 0.65 10.85 7.01

6.86 56.88 2.35 82.31

14.63

-

0.71

-

Element, Weight %

O Al

Cr

Fe

Ni

Pb

Spectrum 1 Spectrum 2 Spectrum 3 Spectrum 4 Spectrum 5

0.50 2.08 0.53

1.04 15.27 11.79 71.41

-

1.90

6.92

6.06 33.99 49.05

1.27 24.30 13.95 59.94

-

18.44 0.84 15.17 11.55 5.03 48.98

9.91

0.33

3.03

1.99

1.08 83.65

Fig. 6. Results of micro-X-ray spectral analysis after exposure of Inconel 601 alloy in molten lead for 240 (a), 720 (b) and 1440 h (c) at 650 °C.

At a temperature of 650 °C, after 240 hours of testing (see Fig. 6a), in the corrosion products, one can observe areas where the nickel concentration (from 75 to 96%) exceeded the nickel concentration in the alloy (60%), while the oxygen concentration was low (from 1 to 3%), which is due to the formation of intermetallic compounds of lead with nickel, and the removal of the latter from the structure of the Inconel 601 alloy. After 720 hours (see Fig. 6b), the process of chemical dissolution of the alloy continued (formation of the "lead-nickel" intermetallic), but an increased oxygen content was already observed in the corrosion products. The low concentration of nickel in the formed layer of corrosion products is probably due to the rapid removal of nickel to the outer surface of the lead melt. It can also be seen that lead diffuses into the surface layers of the Inconel 601 alloy, as a result of chemical dissolution and oxidation of the intergranular boundaries of the alloy. Increasing the test duration to 1440 hours (see Fig. 6c) does not significantly affect the corrosion destruction of the alloy; intensive chemical dissolution of the alloy occurs. In the figure, it is possible to observe how lead diffuses into the surface layer of the Inconel 601 alloy, to a depth of up to 10 μm , which further contributes to the detachment of both individual alloy crystals and entire conglomerates of crystals from the sample, and their diffusion through the melt. Fig. 7 shows the outer surface of the corrosion product layer of an Inconel 601 alloy sample after exposure to molten lead at a temperature of 650 °C for 1440 hours. As can be seen, both individual crystals of nickel oxide and whole conglomerates of its crystals are present on the surface of the lead, i.e. nickel, after chemical dissolution, diffuses through the melt and is oxidized by oxygen on its surface with the formation of the corresponding crystals.