M. H. Loretto, University of Birmingham, Birmingham, United Kingdom; D. Hu, M. Wickins, Q. Li, X. Wu, IRC in Materials Processing, University of Birmingham, Birmingham, United Kingdom
Processing of niobium silicides to produce potential components for use in gas turbines is difficult and most work has used casting, commonly using directional solidification, followed by machining of these difficult-to-machine alloys. In the ULTMAT project, effort was focused on investigating the suitability of conventional ceramic moulds for investment casting of NbSi alloys. Net shape demonstrator blades with different sizes have been successfully cast using the GE MASC alloy and yttria face-coat ceramic moulds. A parallel programme in the IRC was devoted to improve the oxidation resistance through alloying. Some alloys with increased Al concentrations have been studied and they show improvement at both high and low temperatures and at the same time the creep resistance was retained or improved compared to MASC alloy.
