Design of novel interlayers in W-W diffusion-bonded joints for large nuclear shielding components applications

The environment within nuclear fusion reactors is very demanding. The fusion reaction between deuterium and tritium releases approximately 16.6MeV of energy within a plasma, subdivided between a high-energy neutron (~14MeV) and a charged helium nucleus. Neutron irradiation is particularly damaging to the high temperature superconductors (HTSs) in the reactor. A shield, made of W material, is therefore manufactured with the aim to protect the HTS from neutron radiation, as well as thermal fatigue loads from the plasma. Joining W shielding components has proven challenging, due to formation of brittle intermetallic phases and high residual stresses. Consequently, a successful joining methodology has not yet been developed.

This 3-year PhD position will develop an effective joint for W components, utilising a coating interlayer deposited by Physical Vapour Deposition and diffusion bonding as joining method. The chemistry of the coating interlayer and diffusion bonding parameters will be elegantly designed by an Integrated Computational Material Engineering (ICME) approach, through a combination of high-throughput thermodynamic predictions (Thermo-Calc, CALPHAD), Finite Element Analysis (Abaqus) and experimental validations. The work will involve a tight collaboration with the UK Atomic Energy Authority (UKAEA), the industrial sponsor, throughout the project.