NSUF 12-373: Stability of Precipitates under Ion Irradiation

Precipitate stability plays an important role in determining the performance of ferritic-martensitic (FM) steels operating at elevated temperatures. The strengthening precipitates in FM steels primarily refer to MX-type with M = V, Nb, Ta, etc. and X = C/N. Although this type of precipitates have been reported very stable under thermal aging at temperatures up to 650°C, their stabilities under irradiation are not clear. In addition to the strengthening precipitates, it is also important to understand the stability of other major precipitates such as Laves phase in FM steels. This work aims at studying the stability of various precipitates in FM steels under irradiation conditions. To simplify the experiments and reduce the interference from other precipitates during experiments, three model steels, alloyed with W and the elements that form respective MX-type precipitates, have been designed and fabricated. The samples of these model steels will be irradiated using self-ions (Fe2+) at the University of Michigan. A variety of irradiation temperatures and damage doses will be applied to the samples. This study will initially focuses on irradiations at 500°C with a scheduled completion date by September 2012. The ion-irradiated samples will be sent back to Oak Ridge National Laboratory for microstructural characterization to evaluate the precipitate stability under irradiation. A follow-up rapid turnaround proposal focusing on additional irradiation temperatures and alloys will be submitted based on the progress of this work.

Additional Info

Field	Value
Abstract	Precipitate stability plays an important role in determining the performance of ferritic-martensitic (FM) steels operating at elevated temperatures. The strengthening precipitates in FM steels primarily refer to MX-type with M = V, Nb, Ta, etc. and X = C/N. Although this type of precipitates have been reported very stable under thermal aging at temperatures up to 650°C, their stabilities under irradiation are not clear. In addition to the strengthening precipitates, it is also important to understand the stability of other major precipitates such as Laves phase in FM steels. This work aims at studying the stability of various precipitates in FM steels under irradiation conditions. To simplify the experiments and reduce the interference from other precipitates during experiments, three model steels, alloyed with W and the elements that form respective MX-type precipitates, have been designed and fabricated. The samples of these model steels will be irradiated using self-ions (Fe2+) at the University of Michigan. A variety of irradiation temperatures and damage doses will be applied to the samples. This study will initially focuses on irradiations at 500°C with a scheduled completion date by September 2012. The ion-irradiated samples will be sent back to Oak Ridge National Laboratory for microstructural characterization to evaluate the precipitate stability under irradiation. A follow-up rapid turnaround proposal focusing on additional irradiation temperatures and alloys will be submitted based on the progress of this work.
Award Announced Date	2012-07-17T00:00:00
Awarded Institution	None
Facility	None
Facility Tech Lead	Kevin Field
Irradiation Facility	None
PI	Lizhen Tan
PI Email	[email protected]
Project Type	RTE
RTE Number	373