PSI - Issue 42

Petr Dymáček et al. / Procedia Structural Integrity 42 (2022) 1576–1583 Author name / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction The oxide dispersion strengthened (ODS) alloys represent a group of materials for applications at high temperatures up to 1300 °C. Potential fields of application are in 4-th generation of fission or fusion reactors, high temperature grips for testing machines, or even aero jet turbine blades etc. ODS alloys microstructure consists of the metallic matrix strengthened by dispersion of stable yttrium-based oxides of typical size between 5-30 nm and of volume fraction of about 0.5 %. Several commercial alloys have been developed such as MA956 or MA957, PM 2000 or PM2010, ODM alloys and 1DK or 1DS, see Hadraba et al. (2011). The non-commercial, experimental and advanced versions of ODS alloys are ODS Eurofer, 9YWT, 12YWT and 14YWT, see Lindau et al. (2005). Excellent creep strength of the ODS alloys is associated with an attractive interaction between dislocations and oxides. The main disadvantage is the low creep ductility. Stability of Y oxides is guaranteed up to 1300°C, thus they represent a dominant strengthening agent up to this temperature. The aim of this paper is to show the overview of the high temperature mechanical performance of the Fe-Al-Cr Y-O based systems strengthened with yttria oxides up to 5 vol. %. In order to obtain optimized ODS alloy, it is the key to identify the influence of additional metallic Y content and consolidation temperature on the strength and creep properties. Such an investigated ODS nanocomposite is called FeAlOY. Initial trials have been performed with ODS nanocomposites containing 5 vol. % of Al 2 O 3 oxides. It has been studied at high strain rates by Mašek et al. (2016) with promising results. A kinetic study of Fe-Al-O alloy recrystallization was performed by Bártková et al. (2017). The influence of thermomechanical treatment on the grain-growth behavior of new Fe-Al based alloys with fine Al 2 O 3 precipitates was studied by Khalaj et al. (2017). The thermal stability and coarsening of the dispersed Al 2 O 3 and Y 2 O 3 oxides were investigated by Svoboda et al. (2018). It was shown that the stability of Y 2 O 3 precipitates is much better than of Al 2 O 3 at temperatures over 1000 °C. The mechanical properties of FeAlOY up to 800 °C and 1100 °C were studied by Dymáček et al. (2019). Most recent studies of FeAlOY aimed at oxidation resistance, Stratil et al. (2020), and precipitate resistance against coarsening, Holzer et al. (2022), improvement of the mechanical properties and microstructure using hot consolidation by rotary swaging, Svoboda et al. (2020), Chlupová (2020) and optimization of the chemical composition of the powder, Svoboda et al. (2020), Svoboda et al. (2022). The actual creep performance of the new-generation ODS FeAlOY and its comparison with commercial creep resistant alloys is presented in Fig. 1. The technological developments of FeAlOY are ongoing so presumably the mechanical properties are still subject of improvement in the near future.

Fig. 1 Comparison of creep properties of new-generation ODS alloy (rolled, swaged) FeAlOY (n-g ODS) with commercial creep resistant alloys. Note: In Larson-Miller parameter T is temperature in K and t time in hours