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TSNA-C is a nickel-based disk alloy designed around the familiar gamma/gamma-prime superalloy microstructure, but augmented by local phase transformation (LPT) strengthening that activates under creep. During high-temperature service, specific superlattice stacking faults become sites for controlled atomic-scale transformations, which harden those faults, suppress shear pathways (including microtwinning), and slow the mechanisms that typically degrade lifespan due to creep. This fault-level reinforcement is paired with a commercial-ready composition window tuned to balance transformation strengthening with forgeability and heat-treat response, enabling integration into powder-metallurgy routes such as Hot Isostatic Pressing, forging, and standard thermal processing. In NASA development, TSNA alloys formed the expected gamma/gamma-prime microstructure and preliminary tensile and fatigue-crack-growth evaluations at elevated temperature were within acceptable ranges for disk materials. Additionally, phase-stability checks after long-duration exposures showed no deleterious topologically close-packed (TCP) phase formation. Together, properties provide a disk alloy that can sustain higher hot-section demands with a balanced property profile, while fitting the workflows and cost expectations familiar to engine OEMs and suppliers. Forged variants demonstrated markedly improved high-temperature creep behavior, motivating a commercial composition that balances processability with fault-level strengthening. This technology is assessed at a Technology Readiness Level (TRL) 5 and is available for patent licensing.

NASA's new Ni-based superalloy uses a powder metallurgy (PM) composition that inhibits the deleterious gamma-prime to gamma-phase transformation along stacking faults during high temperature creep deformation. Ni-base superalloys have excellent high temperature properties, mostly due to the presence of coherent precipitates. At higher temperatures, these precipitates are defeated by the diffusional shear dislocations producing intrinsic and extrinsic faults. Recent studies have found that, during deformation of turbine disk alloys at high temperature, Co, Cr, and Mo segregate to these faults (removing Ni and Al) inside the strengthening precipitates of these alloys. This represents a local phase transformation from the strengthening precipitate to the weaker matrix phase. Therefore, this elemental segregation significantly weakens the ability of a precipitate to withstand further deformation, producing faster strain rates in the alloy at higher temperatures. This invention presents a solution to prevent this type of segregation along these two faults to improve the creep properties of turbine disks and similar Ni-based alloys. By alloying a specific amount of eta phase formers (Ti, Ta, Nb, and Hf), the phase transformation to can be eliminated along 2-layer extrinsic stacking faults (SESFs) in precipitates without precipitating bulk eta phase. Also, by adding a certain amount of D019 formers (Mo and W), the phase transformation to can be mitigated along 1-layer intrinsic stacking faults (SISFs) without producing bulk sigma phase. This alloy composition incorporates both strengthening methods for use in jet turbine disks, though the composition has applications in other high-stress and/or high-temperature environments as are found in power plants, space launch systems, and other critical structural applications.