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In high temperature applications such as gas turbines, today nickel-base superalloys are commonly employed to fulll the requirements on high temperature creep strength as well as oxidation resistance and toughness. A further improvement in ef ciency of those combustion engines is possible by increasing the turbine inlet temperature or by reducing the density1). Niobium-based silicide composites have been researched for some while now to deliver on both of these prospects. Alloys of this class of materials usually contain a niobium solid solution for ductility and toughness at lower temperatures, or more speci cally at room temperature, and an Nb5Si3 intermetallic phase for high temperature strength. The density of those alloys is typically around 7 g·cm−3 which compares favorably with 9 g·cm−3 for state of the art nickel-base alloys. The binary system, however, while offering suf cient creep strength2,3) suffers from insufcient oxidation resistance4). Alloying elements such as titanium, aluminum, and chromium have been added to improve on that5–8); hafnium is also oftentimes added for solid solution hardening of the niobium phase7). A prominent example of this alloying scheme was the MASC alloy (metal and silicide composite, Nb-16Si-25Ti-2Al-2Cr-8Hf, compositions are given in atomic percent throughout this paper) introduced by Bewlay et al. in 19969). Those alloys, typically produced via induction skull melting (ISM), arc-melting, or directional solidi cation (DS), show a good balance of creep and oxidation properties. As segregations are frequently observed during cast metallurgy of this kind of materials6), castability is often poor, and since near net-shape component production is desirable, powder metallurgy (PM) offers the potential to target all three of these issues. Besides, PM also allows for composition variations that are inaccessible by cast metallurgy38). Therefore, in this work, a MASC-derived composition (Nb-20Si-23Ti-6Al-3Cr-4Hf) was assessed regarding its creep properties and underlying deformation mechanisms after being produced via advanced powder metallurgical techniques. 2. Experimental

Grain Boundary Sliding-Induced Creep of Powder Metallurgically Produced Nb-20Si-23Ti-6Al-3Cr-4Hf