Example of Precipitate Stability in Reactor-Irradiated Nimonic PE16

摘要

Nimonic PE16, a gamma prime (Ni sub 3 (Al,Ti)) precipitate strengthened alloy under consideration for fast reactor structural applications, was reactor irradiated in three heat treatment conditions: solution treated, aged, and overaged. After irradiation at 600 exp 0 C to 5.4 x 10 exp 22 n/cm exp 2 (E > 0.1 MeV), or about 27 dpa, specimens were characterized for gamma prime precipitate stability by transmission electron microscopy. The precipitate microstructures after irradiation were found to be very sensitive to heat treatment prior to irradiation. Precipitates present prior to irradiation remained stable. Additional precipitation occurred in-reactor for each of the specimen conditions examined. The in-reactor gamma prime precipitation process decorated such microstructural features as voids, dislocations and carbide precipitates. It is apparent that a maximum stable precipitate particle size does not exist in this alloy. These results provide a realistic estimate of microstructural alterations to be expected at goal fluences. (ERA citation 04:014036)