Influence of the Pt addition on the microstructure and hardness of cast Ni-based superalloy for aerospace applications

Nickel-based superalloys, such as Rene N5, are commonly used in high-temperature turbine components due to their exceptional mechanical strength and stability. While platinum is recognized for its role in enhancing oxidation resistance and microstructural stability, its impact on mechanical performance has not been thoroughly investigated. This study explores the effects of platinum additions ranging from 0 to 5 wt.% on the microhardness and microstructure of Rene N5 in both as-cast and heat-treated conditions. Thermo-Calc simulations indicated that the additions of platinum influence phase stability and precipitation behavior. Vickers microhardness measurements were conducted under a 0.1 kgf, while light microscopy and scanning electron microscopy (SEM) were utilized for microstructural analysis. In the as-cast state, the highest hardness was recorded for the Pt-free variant (486 HV), with the hardness values of the other compositions ranging from 452 HV to 477 HV. After heat treatment, the hardness generally decreased, resulting in values between 385 HV (for 3% Pt) and 420 HV (for 5% Pt). SEM observations clearly revealed the very distinct presence of intermetallic γ′ precipitates in both dendritic regions and interdendritic spaces.

This work was supported by the National Science Center (Poland) under project “Monocrystalline Ni-based superalloys modified with platinum for the production of critical rotating turbine components of aircraft engines” (2023/51/D/ST11/00945).