EFFECTS OF CARBON AND HAFNIUM CONCENTRATIONS IN WROUGHT POWDER-METALLURGY SUPERALLOYS BASED ON NASA IIB-11 ALLOY

摘要

NASA IIB-11, a candidate alloy for advanced-temperature turbine engine disks, and four modi¬fications of that alloy with various C and Hf concentrations were produced as cross-rolled disks from prealloyed powder that was hot isostatically compacted. The mechanical properties, microstructures, and phase relations of the alloys are discussed in terms of their C and Hf con¬centrations. A low-C and high-Hf modification of IIB-11 had the best balance of mechanical properties for service below about 750° C. However, because of their finer grain sizes, none of the powder-metallurgy alloys produced had the high-temperature rupture strength of con¬ventionally cast and wrought IIB-11.