Microstructure and mechanical behavior of ODS and non-ODS Fe–14Cr model alloys produced by spark plasma sintering

Abstract

In this work the spark plasma sintering (SPS) technique has been explored as an alternative consolidation route for producing ultra-fine grained Fe–14Cr model alloys containing a dispersion of oxide nanoparticles. Elemental powders of Fe and Cr, and nanosized Y2O3 powder have been mechanically alloyed in a planetary ball mill and rapidly sintered in a spark plasma furnace. Two alloys, with nominal compositions Fe–14%Cr and Fe–14%Cr–0.3%Y2O3 (wt.%), have been fabricated and their microstructure and mechanical properties investigated. The results have been compared with those obtained for other powder metallurgy processed alloys of the same composition but consolidated by hot isostatic pressing. The SPS technique under the present conditions has produced Fe–14Cr materials that apparently exhibit different microstructures yielding inferior mechanical properties than the counterpart material consolidated by hot isostatic pressing. Although the presence of a dispersion of Y-rich particles is evident, the oxide dispersion strengthened (ODS) Fe–14Cr alloy consolidated by SPS exhibits poor tensile properties. The extensive decoration of the powder particle surfaces with Cr-rich precipitates and the residual porosity appear to be responsible for the impaired properties of this ODS alloy consolidated by SPS.