Use Of Neutron And X-Ray Diffraction To Study The Precipitation Mechanisms Of Oxides In Ods Materials

It is usually accepted that the formation of nano-clusters inside Oxide Dispersion Strengthened (ODS) materials is due to the dissolution of the yttrium oxide during the mechanical alloying and to the precipitation of the nano-oxides during the consolidation process.A study was conducted to follow the dissolution and the re-precipitation of the phases after mechanical alloying and different heat treatments, A Fe-9Cr powder was milled during different milling times with 10 wt.% of yttria and/or titanium in a planetary mill. Using neutron and X-ray diffractions and the Rietveld method, the dissolution and re-precipitation of yttria was investigated.Even with a content of 10 wt.%, the yttria particles disappear during milling to form a structure which can be described as Fe crystallites coexisting with amorphous domains composed of Y and O atoms. After annealing Y and O atoms re-precipitate into the matrix to form yttria crystallites. (C) 2011 Elsevier B.V. All rights reserved.