The Application of Plasma Transferred Arc (PTA) Powder Deposition Methods to the Fabrication of Dissimilar Metal Transitions

There are many formidable technical challenges associated with the development of prototype fusion reactors, and prominent among these is the need to join a diverse range of dissimilar metals. Tungsten, for example, is a leading candidate for plasma-facing components, while structural components such as the vacuum vessel are likely to be fabricated from either an austenitic stainless steel or a 9-Cr ferritic/martensitic steel. The fusion welding of tungsten in itself is extremely challenging owing to its extremely high melting point, and the joining of tungsten to iron-based structural materials is even more difficult, owing to the extraordinary mismatches that arise in material properties.

Cu-Cr-Zr alloys have been identified as promising materials for fusion applications, owing to their high thermal conductivity and their potential to be metallurgically compatible with a range of fusion-relevant materials. They, therefore, offer the potential to act as an intermediate layer between tungsten-based alloys and either ferritic/martensitic or austenitic stainless steels. However, the best methods for joining Cu-Cr-Zr alloys to various materials are yet to be identified. There is also a challenge associated with the relatively poor creep resistance of Cu-Cr-Zr alloys at temperatures in the vicinity of 400°C and above. Any joining technique would need to be sympathetic to the preservation of creep resistance.

In this project, the aim is to explore the potential for applying plasma transferred arc (PTA) powder deposition technologies to the joining of Cu-Cr-Zr alloys to alloys that may include austenitic stainless steels, tungsten and/or its alloys, and 9Cr ferritic/martensitic steels. PTA deposition offers advantages over alternative technologies in that it is a fusion-based process that leads to minimal heat input to the substrate, which could in turn minimise thermal damage to adjoining materials. The use of Cu-Cr-Zr alloys as both the overlay material and the substrate material will be investigated. The evolution of microstructures and mechanical properties will be characterized in order to identify the optimum strategies (e.g. deposition patterns/sequences) for the deployment of PTA deposition, and the performance of PTA deposits will be benchmarked against alternative joining technologies such as field-assisted sintering technology (FAST). It is expected that this work will lead to publishable outcomes and that it will advance the state of knowledge for dissimilar metal joining of fusion-relevant materials. The successful candidate will gain experience in the fusion technology sector and will emerge with transferable skills and experience with a wide range of materials characterization techniques.

Admissions qualifications/requirements: A 2/1 honours degree or better in materials science, mechanical engineering or a related discipline. Home student.

Deadline: 5 pm on Thursday 24th June.