@article{xu_li_valdez_saber_zhu_koch_scattergood_2016, title={Effect of nano-oxide particle size on radiation resistance of iron-chromium alloys}, volume={469}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2015.11.044}, abstractNote={Radiation resistance of Fe–14Cr alloys under 200 keV He irradiation at 500 °C was systematically investigated with varying sizes of nano oxide Zr, Hf and Cr particles. It is found that these nano oxide particles acted as effective sites for He bubble formation. By statistically analyzing 700–1500 He bubbles at the depth of about 150–700 nm from a series of HRTEM images for each sample, we established the variation of average He bubble size, He bubble density, and swelling percentage along the depth, and found them to be consistent with the He concentration profile calculated from the SIRM program. Oxide particles with sizes less than 3.5–4 nm are found most effective for enhancing radiation resistance in the studied alloy systems.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Xu, Weizong and Li, Lulu and Valdez, James A. and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2016}, month={Feb}, pages={72–81} }
 @article{li_xu_saber_zhu_koch_scattergood_2015, title={Influence of scandium addition on the high-temperature grain size stabilization of oxide-dispersion-strengthened (ODS) ferritic alloy}, volume={636}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.03.117}, abstractNote={The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Xu, Weizong and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2015}, month={Jun}, pages={565–571} }
 @article{li_xu_saber_zhu_koch_scattergood_2015, title={Long-term stability of 14YT-4Sc alloy at high temperature}, volume={647}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.09.012}, abstractNote={14YT alloy (Fe–14Cr–0.25wt%Y2O3–0.4wt%Ti) with 4 at% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 h. Here we report that the microstructure and mechanical behavior of 14YT–4Sc alloy after long-term annealing for up to 60 h at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc–Ti–Y–O enriched nano oxide particles (<10 nm) were observed in EDS mapping of the 14YT–4Sc–60h sample. The nano-structure retention at the high temperature of 1000 °C for 60 h is attributed to these complex nano oxides.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Xu, Weizong and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2015}, month={Oct}, pages={222–228} }
 @article{xu_li_saber_koch_zhu_scattergood_2015, title={Microstructures and Stabilization Mechanisms of Nanocrystalline Iron-Chromium Alloys with Hafnium Addition}, volume={46A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-015-2985-2}, number={9}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Xu, Weizong and Li, Lulu and Saber, Mostafa and Koch, Carl C. and Zhu, Yuntian and Scattergood, Ronald O.}, year={2015}, month={Sep}, pages={4394–4404} }
 @article{li_saber_xu_zhu_koch_scattergood_2014, title={High-temperature grain size stabilization of nanocrystalline Fe-Cr alloys with Hf additions}, volume={613}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2014.06.099}, abstractNote={The influence of 1–4 at% Hf additions on the thermal stability of mechanically alloyed nanocrystalline Fe–14Cr alloys was studied in this work. XRD-calculated grain size and microhardness results were reported versus isochronal annealing treatments up to 1100 °C. Microstructural evolution was investigated using channeling contrast FIB imaging and TEM. Grain size of samples with 4 at% Hf was found to be maintained in the nanoscale range at temperatures up to 1000 °C. Zener pinning was considered as a major source of high temperature grain size stabilization. By comparing the Orowan strengthening contribution to the total hardness, the deviation of grain size predictions from the actual grain size in Fe–14Cr–4Hf suggests the presence of thermodynamic stabilization by the solute segregation to grain boundaries (GBs). A predictive thermodynamic model indicates that the thermodynamic stabilization can be expected.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Saber, Mostafa and Xu, Weizong and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2014}, month={Sep}, pages={289–295} }
 @article{xu_li_saber_koch_zhu_scattergood_2014, title={Nano ZrO2 particles in nanocrystalline Fe-14Cr-1.5Zr alloy powders}, volume={452}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2014.05.067}, abstractNote={Here we report on the formation of nano ZrO2 particles in Fe–14Cr–1.5Zr alloy powders synthesized by mechanical alloying. The nano ZrO2 particles were found uniformly dispersed in the ferritic matrix powders with an average size of about 3.7 nm, which rendered the alloy powders so stable that it retained nanocrystalline structure after annealing at 900 °C for 1 h. The ZrO2 nanoparticles have a tetragonal crystal structure and the following orientation relationship with the matrix: (0 0 2)ZrO2//(0 0 2)Matrix and [0 1 0]ZrO2//[1 2 0]Matrix. The size and dispersion of the ZrO2 particles are comparable to those of Y–Ti–O enriched oxides reported in irradiation-resistant ODS alloys. This suggests a potential application of the new alloy powders for nuclear energy applications.}, number={1-3}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Xu, W. Z. and Li, L. L. and Saber, M. and Koch, C. C. and Zhu, Y. T. and Scattergood, R. O.}, year={2014}, month={Sep}, pages={434–439} }
 @article{saber_xu_li_zhu_koch_scattergood_2014, title={Size effect of primary Y2O3 additions on the characteristics of the nanostructured ferritic ODS alloys: Comparing as-milled and as-milled/annealed alloys using S/TEM}, volume={452}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2014.05.014}, abstractNote={The need for providing S/TEM evidence to clarify the mechanisms of nano-scale precipitate formation was the motivation of this investigation. In this study, an Fe–14Cr–0.4Ti alloy was ball-milled with different amounts of Y2O3 content up to 10 wt.%, and then annealed at temperatures up to 1100 °C. Micron-size Y2O3 particles were substituted for the nano-size counterpart to elucidate the mechanism of oxide precipitate formation. The S/TEM studies revealed that the microstructure of the alloy with 10 wt.% yttria contained amorphous undissolved Y2O3 after ball milling, while a small part of the initial oxide particles were dissolved into the solid solution. Consequently, when the amount of yttria was reduced to 1 wt.%, the amorphous phase of the yttria vanished and the whole content of Y2O3 was dissolved into the BCC solid solution. Defect analysis of precipitates on the annealed samples via S/TEM and micro-hardness studies revealed that the use of micron-size primary oxide particles can produce nano-size precipitates, stable up to temperatures as high as 1100 °C, and uniformly distributed throughout the microstructure. This study indicates that the use of high energy ball milling along with micron-size primary oxide particles can lead to nanostructured ferritic ODS alloys without the use of nano-size primary oxide additions.}, number={1-3}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Saber, Mostafa and Xu, Weizong and Li, Lulu and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2014}, month={Sep}, pages={223–229} }