NSUF 15-563: An atom probe tomography investigation of the response of oxide-dispersion nanoclusters to non-similar friction stir welds

Nanostructured ferritic alloys (NFAs) are promising advanced materials for nuclear applications, due, in part, to the ultra-fine dispersion of Y-Ti-O nanoclusters throughout the matrix. These nanoclusters have been proposed to act as point defect sinks, and preferential nucleation sites for He bubble nucleation that reduce the effects of neutron irradiation when compared to standard steels. However the production of NFAs is complex, requiring a non-equilibrium, mechanical-alloying process route making the alloys time-consuming, expensive, and difficult to produce in complex forms. As a result of this, and the requirement to connect components not fabricated from NFAs, it is necessary to produce joined materials. Standard welding techniques are not viable for these connections, and as such viabilities of techniques such as friction stir welding are required. Friction stir welding (FSW) is a solid-state joining technique, during which severe microstructural changes occur in the material. This can ultimately lead to the dissolution and resolution of the nanoscale dispersoids within the metallic matrix thereby altering the mechanical and radiation-tolerance properties. It is therefore necessary to investigate how these dispersoids respond to FSW with non-similar metals to determine the effect it has on the nanoclusters in the matrix. This proposal aims to examine the microstructural response during friction stir welding of non-similar metals, these being the NFA designated 14YWT, and F82H. We will look to investigate the microstructural changes of the materials in the stir zone, the heat affected zone and the bulk material. Specifically we will seek to examine the size, number density and chemical composition of the NFA nanoclusters in all three regions of the FSW region.

Additional Info

Field	Value
Abstract	Nanostructured ferritic alloys (NFAs) are promising advanced materials for nuclear applications, due, in part, to the ultra-fine dispersion of Y-Ti-O nanoclusters throughout the matrix. These nanoclusters have been proposed to act as point defect sinks, and preferential nucleation sites for He bubble nucleation that reduce the effects of neutron irradiation when compared to standard steels. However the production of NFAs is complex, requiring a non-equilibrium, mechanical-alloying process route making the alloys time-consuming, expensive, and difficult to produce in complex forms. As a result of this, and the requirement to connect components not fabricated from NFAs, it is necessary to produce joined materials. Standard welding techniques are not viable for these connections, and as such viabilities of techniques such as friction stir welding are required. Friction stir welding (FSW) is a solid-state joining technique, during which severe microstructural changes occur in the material. This can ultimately lead to the dissolution and resolution of the nanoscale dispersoids within the metallic matrix thereby altering the mechanical and radiation-tolerance properties. It is therefore necessary to investigate how these dispersoids respond to FSW with non-similar metals to determine the effect it has on the nanoclusters in the matrix. This proposal aims to examine the microstructural response during friction stir welding of non-similar metals, these being the NFA designated 14YWT, and F82H. We will look to investigate the microstructural changes of the materials in the stir zone, the heat affected zone and the bulk material. Specifically we will seek to examine the size, number density and chemical composition of the NFA nanoclusters in all three regions of the FSW region.
Award Announced Date	2015-04-22T00:00:00
Awarded Institution	None
Facility	None
Facility Tech Lead	Yaqiao Wu
Irradiation Facility	None
PI	Chad Parish
PI Email	[email protected]
Project Type	RTE
RTE Number	563