Austenitic stainless steels and high strength copper alloys for fusion components

An austenitic stainless steel (316LN), an oxide-dispersion-strengthened cop per alloy (GlidCop A125), and a precipitation-hardened copper alloy (Cu-Cr- Zr) are the primary structural materials for the ITER first wall/blanket an d divertor systems. While there is a long experience of operating 316LN sta inless steel in nuclear environments, there is no prior experience with the copper alloys in neutron environments. The ITER first wall (FW) consists o f a stainless steel shield with a copper alloy heat sink bonded by hot isos tatic pressing (HIP). The introduction of bi-layer structural material repr esents a new materials engineering challenge; the behavior of the bi-layer is determined by the properties of the individual components and by the nat ure of the bond interface. The development of the radiation damage microstr ucture in both classes of materials is summarized and the effects of radiat ion on deformation and fracture behavior are considered. The initial data o n the mechanical testing of bi-layers indicate that the effectiveness of Gl idCop A125 as a FW heat sink material is compromised by its strongly anisot ropic fracture toughness and poor resistance to crack growth in a direction parallel to the bi-layer interface. (C) 1998 Elsevier Science B.V. All rig hts reserved.