The use of precious-metal-modified nickel-based superalloys for thin gage applications

摘要

Precious-metal-modified nickel-based superalloys are being investigated for use in thin gage applications, such as thermal protection systems or heat exchangers, due to their strength and inherent oxidation resistance at temperatures in excess of 1,050°C. This overview paper summarizes the Air Force Research Laboratory (AFRL) interest in experimental two-phase γ-Ni + γ′-Ni₃Al superalloys. The AFRL is interested in alloys with a based composition of Ni-15Al-5Cr (at. %) with carbon, boron, and zirconium additions for grain-boundary refinement and strengthening. The alloys currently being evaluated also contain 4–5 at.% of platinum-group metals, in this case platinum and iridium. The feasibility of hot rolling these alloys to a final thickness of 0.12–0.25 mm and obtaining a nearly fully recrystallized microstructure was demonstrated.