Small angle neutron scattering analyses and high temperature mechanical properties of nano-structured oxide dispersion-strengthened steels produced via cryomilling

Three oxide dispersion-strengthened (ODS) steels are produced in order to investigate the effect of the mechanical alloying (MA) temperature on the microstructural evolution and high temperature mechanical properties. The microstructural evolution with different MA conditions is examined using small angle neutron scattering. As the MA temperature decreases, the density of the nanoclusters below 10 nm increases and their mean diameter decreases. A low temperature during MA leads to a high strength in the compression tests performed at 500°C; however, this effect disappears in testing at 900°C. The milling process at -70°C exhibits excellent high fracture toughness, which is better than the benchmark material 14YWT-SM10. However, the -150°C milling process results in significantly worse fracture toughness properties. The reasons for this strong temperature dependency are discussed.