Nanostructured Engineering Alloys for Nuclear Application

Abstract

In advanced nuclear applications, high temperature and a corrosive environment are present in addition to a high dose radiation field causing displacement damage in the material. In recent times it has been shown that Nanostructured Ferritic Alloys (NFA's) such as advanced Oxide Dispersion Strengthened (ODS) steels are suitable for this environment as they tolerate high dose irradiation without significant changes in microstructure or relevant mechanical properties. Ion beam irradiation is a fast and cost effective way to induce radiation damage in materials but has limited penetration depth. Therefore, small scale mechanical testing such as nanoindentation and micro compression testing in combination with FIB based sample preparation for micro structural characterization has to be performed allowing a full assessment of the materials' behavior under radiation environment. In this work two different ODS materials have been irradiated using proton and combined proton and He beams up to 1 dpa at different temperatures. Nanoindentation and LEAP measurements were performed in order to assess the changes in properties of these alloys due to irradiation. The same techniques were applied to intermetallic nanostructured alloys in order to investigate the effectiveness of the metal-intermetallic interface to provide defect sinks for He and radiation damage. It was found that irradiation can cause the formation of intermetallic particles even at room temperature while increasing the material strength significantly. 92

An intermetallic forming steel under radiation for nuclear applications

“…The most effective defect sinks and traps have been proven to be interfaces such as grain boundaries or phase boundaries [5][6][7][8]. This information has led to the creation of materials with extremely high interface densities which allow for a more radiation tolerant system by utilizing a high density of nm-sized precipitates or multilayer structures [9][10][11]. The influence of these precipitates or multilayers on the mechanical properties and radiation resistance of the material is controlled by parameters like size, shape, number density or layer thickness and volume fraction.…”