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Title: The development of niobium-silicide based materials for high temperature applications
Author: Dicks, Robert Paul
ISNI:       0000 0004 2690 1149
Awarding Body: The University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2007
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Materials based on the niobium-silicon system, which comprises a niobium solid solution and Nb-Si, intermetallic, have been studied. Research is divided into two areas: the suitability of novel techniques for processing and the development of new compositions to improve material properties. Direct Laser Fabrication (DLF), Hot Isostatic Pressing (HIPping) and Arc-melting are explored. DLF and HIPping can process these materials satisfactorily but do not allow flexible composition control. Arc-melting allows greater compositional flexibility, but has restrictions on sample geometries that can be produced. The oxidation behaviour at 800 and 12000C ofNb-24Ti-16Si-xM, alloys (M = V, Ru or Cr) was studied. The oxidation mechanism differed at the two temperatures, but was not heavily dependent on composition. Additions of V and Ru improve oxidation performance but result in higher stress in the solid solution lattice during oxygen diffusion, which can initiate cracks. Ru additions reduce pesting behaviour at 800°C. Nb-18Ti-19Si-4AI-6Hf-IRu-3V, Nb-18Ti-19Si-4AI-6Hf-IRu-6Cr and Nb-IOTi-19Si- 4AI-4Hf-lRu-3V (at%) alloys were chosen for further study. The oxidation resistance of the Nb-18Ti-19Si-4AI-6Hf-IRu-3V and Nb-l 8Ti-19Si-4AI-6Hf-1 Ru-6Cr alloys exceeded the performance of commercially available Nb-Si materials at 800°C and matched it at 1200oC. Creep properties were also improved. Although the performance ofNb-Si materials has been improved, it is still inferior to that of the Nickel-superalloys.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available