Development and Characterization of Nanoparticle Strengthened Dual Phase Alloys for High Temperature Nuclear Reactor Applications

The core structures of advanced future nuclear reactors require to maintain mechanical integrity to extreme irradiation environments (-400 dpa) and high temperatures up to 700°C. The recently developed nanostructured ferritic alloy (NFA), that is composed of Fe-Cr base matrix and Y-W-Ti nanocluster, showed significant high temperature strength and radiation resistance. But, the extremely low fracture toughness at high temperature is a detrimental problem of NFAs. Therefore, the improvement of fracture toughness of NFA is important subjects for application of NFA to high temperature structural material in future nuclear reactor systems. The objective of this study is to develop the technology for improvement of fracture toughness to apply NFA to core structures in the future nuclear systems. The optimum production process for NFA was suggested by obtaining data of the high temperature mechanical/fractural properties of the newly processed 9Cr-NFA at up to 700℃ and by analyses for the results. The NFA with improved toughness can be used as materials for components in high temperature reactors, such as fuel cladding in SFR, turbine blade in VHTR. The data obtained from microstructural analyses, mechanical testing and toughness testing at high temperature can be valuable reference for the understanding and development of similar materials.