Abstract Scope |
Instead of mechanical alloying that needs days of milling and suffers from contamination, and inhomogeneity, oxide dispersion strengthened (ODS) ferritic alloys, e.g., “14YWT,” were generated with powders from gas atomization reaction synthesis (GARS) of molten Y-containing alloys and a mildly oxidizing atomization gas, producing a Cr-enriched surface oxide. Microscopy of GARS powders revealed that a metastable oxide layer (<50nm) forms on the rapidly solidified powders, controlled by oxygen concentration and droplet cooling during solidification, linked to particle size. If hot isostatic pressed at <800C, trapped powder surfaces become oxygen reservoirs that are released on heating above ~900C for reaction with Y-containing intermetallic compounds within each particle, forming highly stable oxide dispersoids. In this work, alloy composition and O2 levels were varied specifically for consolidation either by solid-state friction/stir shearing with indirect extrusion or by laser-powder bed fusion to enhance oxide dispersion strengthening. Support from USDOE-ARPA-E through Ames Lab contract DE-AC02-07CH11358. |