Interfacial properties of HIP joints between beryllium and reduced activation ferritic/martensitic steel

ITER test blanket modules are the most important components to validate energy production and fuel breeding for future fusion demonstration reactors. Reduced activation ferritic/martensitic steel is recognized as one of the promising structural materials for the breeding blanket systems. Beryllium is a primary candidate plasma facing materials for ITER blanket. In this work, the interfacial properties of Be/reduced activation ferritic/martensitic steel (RAF/Ms) joints were investigated for the first wall of an ITER test blanket module (TBM). The joints were produced by the solid-state hot isostatic pressing (HIP) method. Chromium (Cr) was used as a diffusion barrier with a thickness of 1 μm or 10 μm, formed by plasma vapor deposition on the Be surface. The HIPping was conducted at 1023 K and 1233 K with 160 MPa of static pressure. The temperatures are standard normalizing and tempering temperatures of F82H. EPMA showed the Cr layer effectively worked as a diffusion barrier at 1023 K. However, for the F82H/Be interface which underwent HIP at 1233 K followed by tempering a Be rich layer was formed. Bend tests revealed that a thin Cr layer and low temperature HIP is preferable. The joint with a thick Cr layer suffer from brittleness of Cr itself.