Novel Alloying Strategy to Improve Brazing Properties on Nickel-Based Superalloys for Aircrafts Turbine Application

Abstract

The continuous improvement of high potential repair technologies is an essential driver for cost-effective and sustainable aviation. To withstand extreme forces and temperatures, the turbine section of aircraft engines is made from Nickel-based superalloys. This class of materials routinely develops cracks and geometrical deviations in service, which require a brazing repair, thus making brazing an indispensable key technology. This study seeks to improve brazing properties on Nickel-based superalloys for aircraft applications. Facilitated by materials simulation, a novel alloying strategy is outlined to design the braze alloy chemistry. The design criteria are established on the optimization of major microstructural properties influencing the mechanical properties known for repair brazed joints. The proposed design criteria were applied to the development of two new braze alloys. The new alloy design approach is validated experimentally by using the developed alloys. Mechanical properties of brazed samples made from Nickel-based superalloys were investigated at a service equivalent temperature of 871 °C. Results indicate that the ultimate tensile strength at 871 °C is 20.5% higher than that published for legacy braze alloys. This study provides a basis for the development of repair technologies applicable to further superalloys.