Effect of filler metal chemical composition on the TiAl/IN738 dissimilar brazed joint

Abstract

This paper investigates the microstructure and mechanical properties of dissimilar brazing of γ-TiAl/IN738 superalloy using two different filler metals. The microstructure of the two joints was comprised by the continuous intermetallic layers formed during holding time at the bonding temperature, and even during cooling. It was observed that the presence of the thick continuous brittle phases in the bond region of the IN738/Cu/TiAl joint led to lower mechanical properties in comparison with the IN738/Ni–Si–B/TiAl joint. The fracture occurred in the Reaction Layer(RL)/TiAl interface and the RL/Solidified zone(SZ) interface of the joints using Ni–Si–B and Cu filler metals, respectively. Also, the joint made using Ni–Si–B filler metal exhibited higher shear strength compared to the joint made using Cu filler metal by 20%.

KEYWORDS:

• IN738
• TiAl intermetallic
• brazing
• pure copper
• Ni–Si–B filler metal
• fracture analysis

Acknowledgements

This research was done in EnerMat laboratory at Iranian Research Organization for Science and Technology (IROST). The authors also would like to acknowledge Dr. Reza Gholamipour for his great support with VAR-casting of required TiAl IMC used in this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Funding

This research was done in EnerMat laboratory at Iranian Research Organization for Science and Technology (IROST) [grant number 1012095010]. The authors would like to acknowledge the IROST for funding this research.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Notes

^a Boron could be detected by the EDS in this phase, though it could not be quantified due to the inability of the EDS system for the light elements.