UC Berkeley

Next generation nuclear reactor concepts employ higher temperatures, harder neutron fluxes, and generally a more difficult material environment than the current fleet. This, in conjunction with economic demands for longer periods between outages and higher fuel utilization, require radiation-hardened materials capable of withstanding such conditions. Oxide dispersion strengthened (ODS) steel alloys are one such potential class of materials. These are induced to have nanostructures within their bulk which provide distinct advan- tages, but which also preclude the use of consolidation and joining techniques which would degrade or destroy the same features. Cold spraying is an additive technique which has been explored as a possible avenue toward efficiently creating bulk parts out of ODS-precursor feedstock, with superior efficiency and properties compared to other means of consolidation, most commonly hot extrusion.

This work has assessed the mechanical properties of one very promising ODS alloy, 14YWT, as formed by the cold spray technique. Results were not promising: the samples were brittle and weak, while not completely free of some of the disadvantages of hot extru- sion. Additionally, the demands of the cold-spray process were determined to be distinctly limiting as to the formation of the feedstock material, with negative impacts on the quality of the nanostructuring that forms the unique and desirable feature of the alloy. Though additional material processing and quality control may be able to remediate some of these defects, this work concludes that cold spraying is not a suitable mechanism for consolidating ODS alloys.