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Kim, J.H.,Byun, T.S.,Hoelzer, D.T. North Holland Pub. Co 2013 Journal of nuclear materials Vol.442 No.1
The stress relaxation behavior of 14YWT and ODS-Eurofer97 was examined within the framework of an internal-variable theory of inelastic deformation. Stress versus strain rate curves obtained by stress relaxation tests for 14YWT were described well by the equations for grain-matrix deformation while those of ODS-Eurofer97 were fitted with the combined curves of grain matrix deformation and grain boundary sliding. The sudden drop of total elongation of 14YWT was discussed in light of fracture surface observations. Grain boundary decohesion at 900<SUP>o</SUP>C was identified.
Seol, Jae Bok,Haley, Daniel,Hoelzer, David T.,Kim, Jeoung Han Elsevier 2018 Acta materialia Vol.153 No.-
<P><B>Abstract</B></P> <P>Doping with interstitials influences the grain boundary (GB) composition of metallic alloys, enabling changes in elemental GB enrichment, grain size, and mechanical properties or even promoting nanoparticle formation. Yet, little efforts on these doping effects have been made in oxide dispersion-strengthened (ODS) steels. Here, by combining advanced microscopy techniques, we studied the impact of interstitial concentration and extrusion temperature on the GB structure-dependent solute segregation, Y−Ti−O nanofeatures, and mechanical properties of ferritic Fe–14Cr (wt%) ODS steels fabricated by ball milling. We found that doping with high carbon and oxygen contents causes the GB to be decorated with the interstitials and promotes nanoparticle formation along the GBs, thereby retarding capillary-driven grain coarsening. This effect performs twofold, through grain size refinement and particle hardening. For samples with low interstitial contents, altering the extrusion temperature does not significantly change the material's mechanical properties and microstructure or the nonstoichiometric chemistry of nanoparticles, which are highly stable at high temperatures. Further, for all the samples, Y–Al oxides in the initial precipitation stages rapidly become coarsened at high temperatures, as Al weakens the thermal stability of nanoparticles, thereby transforming them to core-shell structures with Y−Al-rich cores and Ti−O-rich shells in the later precipitation stages.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>