Microstructure and properties of Fe-Cr and ODS-Fe-Cr model alloys

In order to explore the effects of Cr and dispersion strengthening on microstructure and properties, two sets of Fe-Cr-based alloys were investigated. The binary Fe-Cr alloys were obtained by means of furnace melting of industrial pure Fe and Cr [Matijasevic, JNM 377 (2008) 147]. Cr levels are in the range from 2.4 to 11.6 wt%. The ODS-Fe-9wt%Cr alloys were produced by spark plasma sintering starting from industrial elemental powders of Fe and Cr and two different qualities of Y2O3 powder [Franke, Diploma Thesis, TUB Freiberg, 2009]. Milling time (5, 10 and 20 hours) and ODS fraction (0, 0.3 and 0.6%) were varied. For part of the ODS-Fe-Cr alloys an additional HIP treatment was performed in order to reduce porosity. Several techniques including small-angle neutron scattering (SANS) were applied in order to characterize the microstructure of the alloys. Sound velocity measurements, nanoindentation, tensile testing and impact testing were applied in order to characterize the mechanical behaviour. The effects of Cr and ODS on microstructure and properties are reported. Using SANS a significant increase of the scattering cross sections was found in comparison with the respective non-ODS variant. The reconstructed size distribution indicates the presence of ODS particles in the size range from 2 to 20 nm. Significant effects of both Cr content and disperion strengthening on the polycrystalline elastic properties and nanohardness were also observed.