3.5. Materials Development and Test Introduction Materials R&D for ...

Review of the ITER Technology R&D
3.5 Materials Development and Test
For HIP joining the use of CuAl25-IG alloy is preferable due to its excellent resistance to
high temperature heating. Optimised SS/CuAl25-IG joints have good radiation resistance.
Strength of the HIP bonded joints after 0.4 dpa irradiation dose at 150 and 300°C is higher
than or equal to that of the base metal, with the failure location within the Cu part close to the
interface [60].
Properties of CuCrZr/SS joints depend on the properties degradation of Cu alloy due to heat
treatment used for joining technology. Providing fast cooling (~ 1-2°C/s) and applying
further ageing, the properties of CuCrZr-IG after HIP are acceptable [27, 61]. This method
gives high quality bonding and tensile properties of joints close to the strength of Cu alloys.
Other joining methods such as explosion bonding seem promising and provides a good
quality of joint, but it is applicable only for simple geometric shapes of the components. For
Cu tube to stainless steel tube joining, friction welding, diffusion bonding (for DS Cu) and
TIG welding with Ni interlayer (for CuCrZr-IG) can be used. The casting of CuCrZr onto
stainless steel also gives a good quality of joint, that is also resistant to neutron irradiation
[62].
The R&D results obtained for the joints lead to the following relationship of fracture
resistance:
- base material > joint sample > irradiated joint sample,
- CuCrZr joints >>CuAl25 joints,
- lower temperature data > same at high temperature.
However, results are geometry dependent, and the samples do not generally fail at the
interface.
Fusion Engineering and Design Page 24