Proceedings of the 15th International Workshop on Beryllium Technology (BeWS-15) September, 14-15, 2022, Karlsruhe, Germany (KIT Scientific Reports ; 7764)

The 15th International Workshop on Beryllium Technology (BeWS-15) was held as a joint event combining BeWS-15 and industrial forum BeYOND-IX on September 14-15, 2022 in Karlsruhe, Germany with great success as a hybrid event. The workshop was organized by the Karlsruhe Institute of Technology. Participants came from Germany, the US, the UK, Kazakhstan, Latvia, Czech Republic, Japan, Sweden, France and China, totaling 55 persons, which was not expected immediately after the global pandemic

Microstructural insights into EUROFER97 batch 3 steels

Extensive analytical electron microscopical analyses were carried out from the micrometer scale down to the nanometer scale to characterize three variants of the 9% reduced activation ferritic martensitic (RAFM) steel EUROFER97/3. No huge microstructural differences were observed between the three grades. Electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM) was used to determine prior austenite grain (PAG) and lath sizes of the martensite matrix. The PAG size varied between 4.5 µm and 6.5 µm depending on the reconstruction algorithm. Furthermore, the martensitic lath sizes determined by SEM-EBSD are only half or 1/3 of that determined manually from transmission electron microscopy (TEM) images, which might be related to the limited statistics in this type of TEM data evaluations. The SEM-EDX shows that M$_{23}$C$_6$-type phases are preferentially located on lath and grain boundaries due to preferential diffusion of elements like Cr, W, and C to and along grain boundaries, which agrees with TEM-EDX measurements. TEM techniques like STEM-EDX and high-resolution TEM were used to describe the occurring precipitates i.e., M$_{23}$C$_6$, VN, TaC morphologically, structurally, and chemically. In addition, the thermodynamic calculations were carried out to explain phase formation, phase fraction and phase composition. The results are in good agreement with the experimentally determined values. These results will provide a profound basis to explain the mechanical performance of these materials. Furthermore, it will lay a good reference basis of comparison for the material after neutro

Effect of HIP at 1000–1200 °C on microstructure and properties of extruded Be-Ti composites

Solid titanium beryllide blocks will be used for neutron multiplication in the helium-cooled pebble bed (HCPB) blanket concept of EU DEMO. A combination of hot extrusion of Be-Ti powders and subsequent hot isostatic pressing (HIP) of the obtained Be-Ti composites has been proposed for manufacturing such blocks. This work is devoted to the study of the effect of HIP at 1000–1200 °C on the structure and properties of Be-Ti composites in order to optimize the HIP parameters. The HIP at 1000–1200 °C resulted in an almost single-phase titanium beryllide (TiBe$_{12}$) with small amounts of Be and other phases, which gradually dissolve with an increase in the HIP temperature. Such a treatment at 1000 and 1100 °C provides a very fine-grained microstructure of TiBe$_{12}$ with an average grain size of 0.3 and 0.6 μm, respectively. The resulting titanium beryllide is characterized by high microhardness of 1350–1480 HV$_{0.1}$ depending on the HIP temperature. According to the nanoindentation tests of the Be-Ti composite after HIP at 1100 °C, the indentation modulus of TiBe$_{12}$ can be estimated as 295 GPa. The fracture toughness of the TiBe$_{12}$ was determined as 1.5–1.7 MPa·m$^{1/2}$. The temperature of 1100 °C was chosen as optimal for the HIP of Be-Ti composites after hot extrusion. The titanium beryllide obtained in this way was used to manufacture a reduced size mockup of Ø20 mm × 18 mm. The mockup has no visible surface defects and can be used for further experiments

Lanthanum plumbide as a new neutron multiplier material

A new neutron multiplier based on lanthanum plumbide LaPb3 was produced using two different casting methods. The argon-arc melted material consists of LaPb3 dendrites between grains of LaPb2 phase of approximately equal volume fraction. The induction melted material is composed primarily of large LaPb3 grains, about 80 μm in size. Corrosion testing at 20 and 300 °C in air revealed the rapid degradation of LaPb3 without the formation of a protective passivation layer. The corrosion process results in significant volumetric expansion accompanied by cracking. When LaPb3 is exposed to air at 500 °C, pure lead as a corrosion product melts to form layers protecting against rapid corrosion. LaPb3 showed low (113–193 MPa), but sufficient strength for functional use in the temperature range of 20–500 °C

Beryllium intermetallics: Industrial experience on development and manufacture

Ulba Metallurgical Plant JSC has been leading several research and development programs aimed at producing beryllides for both structural and fusion applications. The main focus has been on the development of tantalum beryllide as a high-temperature material, and chromium and titanium beryllides as neutron multipliers for EU DEMO. Utilizing vacuum hot pressing, billets of tantalum, chromium, and titanium beryllides were successfully produced, with their key properties such as density, phase composition, and microstructure extensively analyzed. These results show promising potential for expanding the use of beryllides and developing new compositions, highlighting the continued importance of research in this area

Microstructural insights into EUROFER97 batch 3 steels

Extensive analytical electron microscopical analyses were carried out from the micrometer scale down to the nanometer scale to characterize three variants of the 9% reduced activation ferritic martensitic (RAFM) steel EUROFER97/3. No huge microstructural differences were observed between the three grades. Electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM) was used to determine prior austenite grain (PAG) and lath sizes of the martensite matrix. The PAG size varied between 4.5 µm and 6.5 µm depending on the reconstruction algorithm. Furthermore, the martensitic lath sizes determined by SEM-EBSD are only half or 1/3 of that determined manually from transmission electron microscopy (TEM) images, which might be related to the limited statistics in this type of TEM data evaluations. The SEM-EDX shows that M23C6-type phases are preferentially located on lath and grain boundaries due to preferential diffusion of elements like Cr, W, and C to and along grain boundaries, which agrees with TEM-EDX measurements. TEM techniques like STEM-EDX and high-resolution TEM were used to describe the occurring precipitates i.e., M23C6, VN, TaC morphologically, structurally, and chemically. In addition, the thermodynamic calculations were carried out to explain phase formation, phase fraction and phase composition. The results are in good agreement with the experimentally determined values. These results will provide a profound basis to explain the mechanical performance of these materials. Furthermore, it will lay a good reference basis of comparison for the material after neutron irradiation

Swelling of Highly Neutron Irradiated Beryllium and Titanium Beryllide

The swelling of beryllium and titanium beryllide after irradiation at 70–750 °C to neutron fluences of (0.25–8) · 1022 cm−2 (E > 1 MeV) was measured using methods of immersion, dimension, and helium pycnometry. Dependences of the swelling on the irradiation temperature and neutron dose were plotted and analyzed. The dose dependences show linear dependences of the swelling for all irradiation temperatures except 70 °C, where the swelling rate varies, depending on increasing neutron dose. Be-7Ti shows much less swelling than pure Be. Irradiation at 430–750 °C to neutron fluence of 1.82 · 1022 cm−2 (E > 1 MeV) leads to swelling of Be at about 50%; for Be-7Ti, it is 2.7%. The microstructure study shows that the formation of bubbles and pores in beryllium occurs much more intense than in titanium beryllide

Tritium Desorption Behavior and Microstructure Evolution of Beryllium Irradiated at Low Temperature Up to High Neutron Dose in BR2 Reactor

The present study investigated the release of tritium from beryllium irradiated at 323 K to a neutron fluence of 4.67 × 1026 m−2 (E > 1 MeV), corresponding up to 22,000 appm helium and 2000 appm tritium productions. The TPD tests revealed a single tritium release peak during thermal desorption tests, irrespective of the heating mode employed. The tritium release peaks occurred at temperatures ranging from 1031–1136 K, depending on the heating mode, with a desorption energy of 1.6 eV. Additionally, the effective tritium diffusion coefficient was found to vary from 1.2 × 10−12 m2/s at 873 K to 1.8 × 10−10 m2/s at 1073 K. The evolution of beryllium microstructure was found to be dependent on the annealing temperature. No discernible differences were observed between the as-received state and after annealing at 473–773 K for 5 h, with a corresponding porosity range of 1–2%. The annealing at temperatures of 873–1373 K for 5 h resulted in the formation of large bubbles, with porosity increasing sharply above 873 K and reaching 30–60%