Nano-indentation has been used since 1970th to investigate the fundamental aspects of mechanical behavior because of its ability to probe at the nanometer scale, thus avoiding impact of natural defects present in real-life crystals and delivering their true properties. Nowadays, the application of nano-indentation in nuclear materials science rapidly emerges because: (i) it is non-destructive method allowing to deduce important mechanical characteristics; (ii) it utilizes extremely small volume of probing material; (iii) such compact setup is capable to perform variety of mechanical loads including high temperature testing. Thus, the nano-indentation techniques is proposed to characterize the impact of neutron irradiation on mechanical properties of materials, and in particular to be applied for primary candidates structural materials for future nuclear applications where neutron loads are especially high.
Design and construction of future reactors like ITER or MYRRHA are extremely ambitious projects which have huge impact on engineering science development, industrial engagement and social perception of energy extracted by efficient and safe nuclear operation. Development and qualification of structural materials for these future nuclear systems require one to demonstrate that after neutron irradiation the material mechanical properties sustain at the acceptable safety limit. That's why R&D to design new materials with dedicated microstructure to resist neutron damage are ongoing. Down selection of these innovative materials requires fast, efficient, accurate and financially competitive testing procedures. This is where the nano-indentation techniques (NIT) can play its role.
Thanks to a possibility to probe a volume in a range of one to several micrometers, the NIT enables the usage of accelerated heavy ion irradiation which can be applied to surrogate the neutron damage. Given appropriate irradiation conditions and proven NIT procedure it is possible to speed up the design of new materials tremendously.
The present project concerns with the application of NIT for mechanical testing of structural materials for future fusion and fission applications. It is well known that nano-indentation process involves generation of dislocations from the indenter tip which "probe" the response of a material, expressed through the interaction of those indent-induced dislocations with the actual material microstructure. Thus deducing the "true" properties of the material requires subtracting the deformation induced by indent itself. In each material and depending on test temperature, the indent-induced deformation has a unique pattern. Correspondingly, the process of nano-indentation should be modelled by appropriate tools and which should account for the presence of both original and irradiation induced microstructural defects. This project is dedicated to the development of the expertise on modelling and experimental testing by means of nano-indentation.
The computational model will be developed in collaboration with University of Liege (leading university), whereas experimental NIT measurements will be performed at UCL (partner university). To provide data for validation, SCK-CEN will utilize mechanical/microstructural facilities and computational expertise to assess the impact of irradiation on mechanical properties.