Surface Processing for Enhanced Environmental and Creep-Fatigue Resistance

The applicant is proposing a novel, industrially-scaleable process for cost-effectively achieving surface alloying and microstructural optimization at selected areas of semi-finished superalloy components. The proposed approach involves (1) electrochemical deposition, followed by, (2) mechanical alloying via surface deformation, and (3) thermal treatment processes to achieve optimum degradation-resistant wrought microstructures. This novel process draws on the applicant’s proprietary grain boundary engineering (GBE) technology, which involves the strategic application of thermo-mechanical metallurgical processing to achieve a high fraction of “special”, low-energy, degradation-resistant grain boundaries in the alloy microstructure. The GBE technology was recently demonstrated (in a 2006 NASA Phase I SBIR program) to significantly improve the high temperature creep performance of conventional wrought Inconel 718 by markedly reducing the susceptibility of the alloy to intergranular crack initiation and propagation. The objective of this program is to evaluate the feasibility of incorporating surface alloying of Platinum (Pt) with the GBE surface treatment to achieve a homogeneous, fully recrystallized (wrought) Pt-alloyed (approx. 10wt%) microstructure in the near surface of the PM superalloys, ME3 and RR1000. The combined and possibly synergistic effects of Pt-alloying and increased content of “special” degradation-resistant grain boundaries is expected to yield environmental and creep-fatigue performance in gas turbine engine hot-section components beyond current limitations, and contribute to the advancement of next generation Air Force propulsion systems.