Microstructural characterization and strengthening mechanisms of a 15Cr-ODS steel produced by mechanical alloying and Spark Plasma Sintering.

Abstract The microstructure of the oxide dispersion strengthened (ODS) Fe-15Cr ferritic steel with Ti and Zr additions was characterized using transmission electron microscopy (TEM), elemental mapping, synchrotron small angle X-ray scattering (SAXS) and electron backscatter diffraction (EBSD) techniques. The results showed that bimodal grain size distribution in the matrix was observed, which is attributed to the heterogeneous recrystallization process during the Spark Plasma Sintering (SPS). TEM and SAXS results showed that very high density nanoscale oxides are formed in 15Cr-ODS steel. Large concentration of nm-scale trigonal-phase Y 4 Zr 3 O 12 oxides and some large oxides of monoclinic CrTi 2 O 5 are observed in specimen by high resolution TEM (HRTEM) and Energy-dispersive X-ray spectroscopy (EDS) mapping. Finally, the yield stress was experimentally measured and quantitatively estimated. The findings indicated that theoretical calculation was in accordance with the experimental results, and strengthening contributions from solute atoms, grains boundaries, dislocations and oxides was presented. [ABSTRACT FROM AUTHOR]