Ni-16Mo and ODS alloys were fabricated by the powder metallurgical processes, and their microstructures and tensile properties were investigated. Ni-16Mo-7Cr and Ni-16Mo-7Cr-0.3Ti-0.35Y₂O₃ (in wt.%) alloys were prepared by mechanical alloying, uniaxial hot pressing, and heat treatment processes. Microstructural observations of these alloys revealed that the Ti and Y₂O₃ additions to a Ni-16Mo alloy were significantly effective to refine the grain size and form nano-sized Y-Ti-O oxide particles. Consequently, the tensile strengths at room temperature and 700°C were considerably enhanced. This improvement of tensile properties can be mainly attributed to the formation of nano-sized oxide particles, as well as the refined grain size. It is thus concluded that Ni-16Mo alloy with Ti and Y₂O₃ additions would be very effective in improving the mechanical properties especially at elevated temperatures.

In present study, Fe-22Cr-4.5Al oxide dispersion strengthened ferritic alloys were fabricated using a pre-alloyed powder with different minor alloying elements, and their microstructures and tensile properties were investigated to develop the advanced structural materials for high temperature service components. Planetary-typed mechanical alloying and uniaxial hot pressing processes were employed to fabricate the Fe-Cr-Al oxide dispersion strengthened ferritic alloys. Microstructural observation revealed that oxide dispersion strengthened ferritic alloys with Ti, Zr additions presented extremely fine micro-grains with a high number density of nano-scaled oxide particles which uniformly distributed in micro-grains and on the grain boundaries. These oxide particles were confirmed as a fine complex oxide, Y2Zr2O7. These favorable microstructures led to superior tensile properties than commercial ferritic stainless steel and oxide dispersion strengthened ferritic alloy with only Ti addition at elevated temperature.