High Resolution Transmission Electron Microscopy of Irradiation Damage in Inconel X-750

The effects of irradiation on Inconel® (Inconel is a registered trademark of Special Metals Corporation and its subsidiaries) X-750, have been shown to lead to embrittlement and intergranular fracture. This is now widely accepted to be a result of intergranular helium bubbles over the fluence range studied. This paper provides a quantitative assessment and a detailed discussion of the radiation-induced defects including; helium bubbles (size and density distribution, and grain boundary area fraction), dislocation loops and stacking fault tetrahedra, and the disordering and dissolution of secondary gamma prime precipitates. The microstructural evolution will be presented and discussed as a function of dose (from ~5.5 to ~80 dpa), helium concentration (~1300 to ~25,000 appm helium), and irradiation temperature (~120–280 to ~300–330 °C).