Mechanical properties of a neutron irradiated nano-structured ferritic alloy

Full text of publication follows: Advanced nano-structured ferritic alloys (NFAs) containing a high density of ultra-fine (2-5 nm) nano-clusters enriched in Y, Ti, and O are considered promising candidates for structural components in future nuclear systems. The microstructure of a NFA is composed of nano-meter sized regions rich in Y, Ti, and O uniformly distributed in a ferritic matrix. The high number density of nano-clusters in NFAs are responsible for their superior tensile strengths compared to conventional ODS ferritic alloys and may provide effective trapping centers for point defects and transmutation products produced during neutron irradiation. This paper summarizes irradiated and unirradiated mechanical properties of an advanced NFA, designated 14YWT, currently being developed at Oak Ridge National Laboratory. In addition to the superior tensile properties, recent experimental results have also indicated 14YWT has very unique and favorable fracture toughness properties down to liquid nitrogen temperatures. For this study an identical alloy to 14YWT, designated 14WT, was produced without nano-cluster dispersions in order to quantify the effect of the nano-clusters on mechanical properties and microstructure. Mechanical properties characterization, including unirradiated and irradiated tensile, fracture toughness, and hardness data, will be presented for each alloy along with preliminary microstructure characterization results. Research at Oak Ridge National Laboratory (ORNL) was sponsored by the U.S. Department of Energy Office of Fusion Energy Sciences, the U.S. Department of Energy Office of Nuclear Energy Science and Technology, and the ORNL SHaRE Facility, which was supported in part by the Division of Scientific User Facilities, O e of Basic Energy Sciences, U.S. Department of Energy. ORNL is managed by UT-Battelle, LLC for the U.S. Department of Energy under Contract DE-AC05-00OR22725. (authors)