Metallurgical characterisations of CMSX-4 vacuum-brazed with BNi-2 and BNi-9

Abstract

High temperature brazing of nickel-based superalloys often produces joints containing hard, brittle micro-constituents that can be detrimental to mechanical properties and challenging to characterise consistently. In this study, techniques including low angle micro-sectioning, image analysis with ImageJ and electron probe micro-analysis were used to determine the composition, hardness and dispersion parameters of phases in single crystal superalloy CMSX-4, vacuum furnace brazed with BNi-2 and BNi-9 filler metals (FMs). Both FMs produced similar joints with hard centreline eutectic phases, a soft isothermally solidified zone and boron diffusion-affected zone in the CMSX-4. The volume fraction, particle size distribution and inter-particle spacing data generated will provide a framework for future metallurgical characterisations and assist in the development of microstructure–mechanical property relationships.

Keywords:

• Superalloys
• Single crystal alloys
• Brazing
• High-temperature brazing
• Braze joint
• Microstructure
• Metallurgical characterisations

Acknowledgements

This research has been supported by Rolls-Royce Corporation and performed within the Manufacturing and Materials Joining Innovation Center (MA2JIC), a U.S. National Science Foundation, Industry-University Cooperative Research Center. Electron probe micro-analysis was performed by Paul Carpenter at Washington University in St. Louis.

ORCiD

B. Riggs http://orcid.org/0000-0002-4988-3188

Additional information

Funding

This work was supported by the National Science Foundation [GRT00038655] and Rolls-Royce Corporation [GRT00040695].