Periodic Reporting for period 1 - INNUMAT (Innovative Structural Materials for Fission and Fusion)
Période du rapport: 2022-09-01 au 2024-02-29
Fission lead-cooled and molten-salt fast reactors are among the Generation IV nuclear reactors under development globally. In addition to fission reactors harnessing the splitting of nuclei, fusion reactors leveraging the combination of two light nuclei are also under development, promising vastly greater amounts of energy released. The EU-funded INNUMAT project will develop innovative structural materials / material solutions for these nuclear applications and with potential applicability in concentrated solar power and/or in hydrogen confinement. The goal is to rapidly increase the technology readiness of the materials regarding corrosion resistance, high temperature strength, thermal stability and irradiation tolerance via computational and experimental high throughput material screening methods.
Within the reporting period, the REFERENCE variants of the innovative materials / material solutions pursued were produced (Co-free HEAs, AFA steels), in-kind provided (15-15Ti and Eurofer substrate materials, ODS steels) and purchased (weld overlay). The REFERENCE materials were then distributed and delivered to the partners involved in their advanced characterization according to the needs identified based on the test matrices beforehand discussed and agreed for the planned investigations on (a) compatibility with various heavy metal and molten salt coolants, (b) mechanical and thermal stability and (c) radiation tolerance. Moreover, the material flow for producing coated materials specimens (coated 15-5Ti and coated Eurofer) was determined. The samples preparation for these investigations including those for the planned ion and neutron irradiations was started and partly finished. The testing setups and loops were prepared and preliminary mechanical and compatibility tests were conducted.
Aiming at deep, beyond state of the art understanding of main mechanisms determining corrosion, mechanical behavior, aging, and degradation of properties due to irradiation first specimens for advanced corrosion analysis were selected and the mechanisms and models to be considered and experiments needed for validation were identified. In addition, conceptual and preparatory work was conducted for advanced microstructural characterization of irradiation effects and simulation experiments of selected mechanisms, e.g. in-situ TEM irradiation to study irradiation induced recrystallization of amorphous coatings and He implantation to study He effects in ODS steels. Furthermore, simulation methods adapted to all the different time and space scales were developed for modelling irradiation damage and microstructure evolutions in a representative HEA system.
To accelerate the development of NEW materials kinetic models for creep and alumina forming, statistical data mining by machine learning, computational thermodynamics (Thermo-Calc, CALPHAD) as well as genetic algorithm for multi-objective optimization were utilized to design new HEAs with optimized resistance to irradiation, creep and corrosion. Accordingly, sample ingots were produced for prelaminar characterization and validation. Similar progress was achieved in the development of new high entropy stabilized amorphous, yttria-doped alumina coating as well as coating with multilayer architecture based on the stack of a ceramic and a metal. The use of small punch test (SPT) as a high throughput method for material characterization and screening in the INNUMAT neutron irradiation programme was prepared by validating the miniaturized, non-standardized specimen selected in dedicated experimental and finite element (FE) simulation activities. To support the rapid development of new HEAs data base for point defects properties in CrFeMnNi system was developed by ab initio atomic scale modelling.
The activities on establishing accelerated qualification roadmaps including guidelines for standardization of Small Specimen Test Techniques (SSTT), among others SPT, started with describing the requirements towards material properties and identifying the input data for the development of qualification and standardization strategies. In addition, an overview was created on state of the art of new test methods that potentially allow acceleration of the qualification process of an innovative material solution. Moreover, the development of guidelines for in-Situ (SEM), micro-tensile and micro-creep testing techniques was initiated with investigations on preparation of specimens with sufficient quality.
Aiming at deep, beyond state of the art understanding of main mechanisms determining corrosion, mechanical behavior, aging, and degradation of properties due to irradiation first specimens for advanced corrosion analysis were selected and the mechanisms and models to be considered and experiments needed for validation were identified. In addition, conceptual and preparatory work was conducted for advanced microstructural characterization of irradiation effects and simulation experiments of selected mechanisms, e.g. in-situ TEM irradiation to study irradiation induced recrystallization of amorphous coatings and He implantation to study He effects in ODS steels. Furthermore, simulation methods adapted to all the different time and space scales were developed for modelling irradiation damage and microstructure evolutions in a representative HEA system.
To accelerate the development of NEW materials kinetic models for creep and alumina forming, statistical data mining by machine learning, computational thermodynamics (Thermo-Calc, CALPHAD) as well as genetic algorithm for multi-objective optimization were utilized to design new HEAs with optimized resistance to irradiation, creep and corrosion. Accordingly, sample ingots were produced for prelaminar characterization and validation. Similar progress was achieved in the development of new high entropy stabilized amorphous, yttria-doped alumina coating as well as coating with multilayer architecture based on the stack of a ceramic and a metal. The use of small punch test (SPT) as a high throughput method for material characterization and screening in the INNUMAT neutron irradiation programme was prepared by validating the miniaturized, non-standardized specimen selected in dedicated experimental and finite element (FE) simulation activities. To support the rapid development of new HEAs data base for point defects properties in CrFeMnNi system was developed by ab initio atomic scale modelling.
The activities on establishing accelerated qualification roadmaps including guidelines for standardization of Small Specimen Test Techniques (SSTT), among others SPT, started with describing the requirements towards material properties and identifying the input data for the development of qualification and standardization strategies. In addition, an overview was created on state of the art of new test methods that potentially allow acceleration of the qualification process of an innovative material solution. Moreover, the development of guidelines for in-Situ (SEM), micro-tensile and micro-creep testing techniques was initiated with investigations on preparation of specimens with sufficient quality.
• Very promising preliminary results on REFERENCE materials (HEA-1, Al203 reference coatings) showing a good mastering of their production and a set of properties (mechanical, microstructural) in agreement with the expectations
• Small punch tests carried out in air, liquid Pb and liquid LBE at application relevant temperatures show that the REFERENCE HEAs, HEA-1 and HEA-3 appear sensitive to Liquid Metal Embrittlement (LME) with the observation of premature fracture and brittle intergranular fracture in presence of the both heavy liquid metals (HLMs). This indicates the need of new HEAs with improved compatibility with HLM coolants.
• No LME in lean AFA steel was observed in small strain rate tensile tests conducted in liquid Pb and liquid LBE at application relevant temperatures. The cubic FCC structure of the alloys and their ability to form a sufficiently protective oxide in the Pb and LBE environments are believed to be the reason that they remained unaffected by LME.
• Quantitative modelling of irradiation induced defects adapted to CrFeMnNi system alloys including data base for point defects properties developed by ab initio atomic scale modelling. This will largely support the interpretation of the results within the planned investigations on irradiation tolerance of HEAs as well as the envisaged accelerated development of new HEAs with optimized resistance to irradiation.
• Small punch tests carried out in air, liquid Pb and liquid LBE at application relevant temperatures show that the REFERENCE HEAs, HEA-1 and HEA-3 appear sensitive to Liquid Metal Embrittlement (LME) with the observation of premature fracture and brittle intergranular fracture in presence of the both heavy liquid metals (HLMs). This indicates the need of new HEAs with improved compatibility with HLM coolants.
• No LME in lean AFA steel was observed in small strain rate tensile tests conducted in liquid Pb and liquid LBE at application relevant temperatures. The cubic FCC structure of the alloys and their ability to form a sufficiently protective oxide in the Pb and LBE environments are believed to be the reason that they remained unaffected by LME.
• Quantitative modelling of irradiation induced defects adapted to CrFeMnNi system alloys including data base for point defects properties developed by ab initio atomic scale modelling. This will largely support the interpretation of the results within the planned investigations on irradiation tolerance of HEAs as well as the envisaged accelerated development of new HEAs with optimized resistance to irradiation.